Hey all,
I redid some of the calculations for the "which mundus and armor trait is optimal for DPS" question below here. For players who don't want to see the math, you can skip to the TLDR section at the bottom of this post.

I redid some of the calculations for Mundus stones and Divines vs Infused under Horns of the Reach as the calculations done before do not take infused and warhorn into account for all calculations. @Asayre, I warmly invite you to comment and correct me if I am wrong anywhere, but I got different results than yours and came to different conclusions than you.

First of all, here are the sources I used:
http://tamrielfoundry.com/topic/introduction-to-pve-damage-calculation-homestead/ by Asayre
http://esoitem.uesp.net/viewSkills.php by UESP

An infused large piece gives 20% of 868 magicka = 173.6 extra.
If you are an altmer/breton magsorc using bound aegis and inner light and have max cp and 5/1/1 gear weight + undaunted passives, you get a 10+8+7+6% magicka bonus. In a raid, warhorn will be giving you another 10% on top most of the time. Let's assume that buff will be up 90% of the time so the increase is 9%. This is a total of 40% from skills and 20% from cp.

This means a large infused piece will net you 173.6 * 1,2 (cp) * 1,4 (skills) = 291.6 magicka.
Without bound aegis this will be 275 magicka.

How much dps increase magicka gives depends on the skill. It scales proportionally to the sum of max magicka and ~10,5 * the spell damage.
Call this the combined damage metric (CDM).

• at CDM 70k (which is achieved with 3k spell damage and 38.5k max magicka) big infused gives a boost of 0.4166%.
• at CDM 80k big infused gives a boost of 0.3645%
• at CDM 60k big infused gives a boost of 0.4860%

For instance, on my Pet Sorc with 5 necropotence + 4 Moondancer + 2 Maw of the Infernal, using bound aegis, inner light and 5/1/1 armor and only Major Sorcery buff , I have 51836 max magicka and 2983 spell damage (CDM 83175,5), and I would change one big divines piece to infused, it would give me a 0,35% damage increase (not regarding the loss of divines).
On my MagDK with 5 juli + 5 bsw + 1 slimecraw, 5/1/1 armor and major sorcery, I have 3152 spell damage (w/o bsw proc) and 41391 magicka (CDR 74487) if I would swap one big piece to infused I would get a 0,37% damage increase.

If you have a lot of max magicka and/or spell damage, infused gives less result than a multiplicative increase such as crit or penetration.

Now the comparison of Infused with Divines under all mundus stones that increase damage.

The Mage:
the Mage gives an increase of 2028 magicka. Every divines piece gives a flat increase of 152,1; this is less than the 173,6 we got with infused. On small pieces we get 351*0.2=70.2 extra, which is less so on small pieces divines is preferred.
TLDR:

The Thief:
Divines gives a 7.5% bonus to 7% crit, which in total is 0,525% crit extra per divines piece.
If we have an average crit modifier of 1,75 (this includes elfborn, and maybe some aggressive horn uptime or other skills) this means we get a dps boost of 0.39%.

The Apprentice:
If you have a sorc with 3 sorc skills slotted, and major sorcery up you get a bonus from divines which is 238*0,075*1,26 = 22,5 spell damage. With minor sorcery from templar that is 23,4 spell damage.
if the rule still applies that spell damage * 10,5 = max magicka, then it would be the equal to 245.5 magicka.
So infused is strictly better than divines on big pieces if you use apprentice (as infused gives 291.6 magicka for aegis users and 275 for non aegis users).
for small pieces this does not count.

The Lover:
Lover gives 2752 penetration. Each divines piece gives 206.4 additional penetration.
Now the formula for mitigation for level 50 mobs from Asayre (see link above) is:
Mitigation = (resistance * (1 - %penetration) - penetration) / 50000.
This means that 206.4 resist gives 0.004128 mitigation (and 206.4 spell pen gives a 0.4128% damage boost).
Of course this assumes full pen is not overcome.
Since most mobs have resist ~18.2k, if alkosh (3k), infused crusher(2108), concentration(4884) and major breach (5280) are up all the time then lover overpenetrates if you use divine small pieces.
Even assuming alkosh is up a reasonable time even on lover infused > divines on large pieces.
if the tank is using torugs + infused crusher (2740) then the resistance left will be larger and more divines become relevant.
Only in pug dungeons were no alkosh or torugs is present lover + 7 divines seems good.
Also some more penetration might be achieved by having CP in spell erosion.

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Now as to which mundus to choose from thief, shadow, apprentice and mage. The lover is left out of this as it is clearly the winner if you have not achieved full spell pen and otherwise it is kind of bad.

- Apprentice
with 4 divines on small pieces (we saw that infused was better on big pieces) gives 238*1,3=309,4 spell damage; with major and minor sorcery this becomes 309.4*1,25 = 387. this is equal to 386*10,5=4061 max magicka.
- Mage
with 4 divines gives 2028 * 1,3 (4 divines) * 1,2 (if full CP) = 3163,68; with inner light 7%, racial 10%, undaunted 6% and warhorn 9% it totals to 4176,05 magicka; in this case it is better than apprentice. With warhorn uptime less than 65% it is worse. With bound aegis it is even better and with pets, who scale almost solely off max magicka, it also becomes better.
- Thief
with 4 divines gives 7*1.3=9.1% crit;
with 7 divines gives 10.675%.
with a crit modifier of 75% this gives a 6.8% (4 divines) resp. 8.0% (7 divines) dps increase.

For Mage to beat Thief with 7 divines, the 4176,05 max magicka needs to be 8% or more of your total CDM. Thus, your CDM needs to be 52200 or less. for 4 divines, your CDM needs to be 61413 or more for thief to beat mage.
For shadow to beat thief, your critical damage modifier needs to be lower than your critical strike chance. Stuff like elfborn, major/minor force, and templar/nightblade passives come into play here.

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TLDR:
- if you use mage or apprentice, infused is always better on large pieces and divines on small.
- if you use thief or shadow it depends on your stats if infused or divines is better on large pieces.
- if you use lover divines is usually better unless you have achieved full penetration.
- The Mage mundus beats apprentice most of the time; Apprentice is only better with warhorn uptime less than 65%. If you use pets or bound aegis, mage is also better.
- thief beats mage and apprentice if you have lots of spell power and max magicka. If without mundus, your (spell damage * 10,5 + max magicka) > ~60k then you should use thief (or shadow if your crit chance is higher than your crit mod)
- Lover is better in non-raid scenarios iff you can profit from all the penetration it provides (nothing new here). In raids with infused crusher, torug, alkosh, minor + major breach etc. you should put a few points in spell erosion and you're better off with another mundus.