That sounds right. I just tried a few Mag Sorc parses and averaged around 115k with 5 light and 2 medium armor. My frag weave is not the best, and I didn't take the time to farm crit or frag procs, so I'd guess that's about 95 percentile. I'm sure that 120k+ is possible, maybe 125k with some practice and luck.

Don't worry about Relequen on a mag build, the useless line of Stamina on the perfected 5pc makes it no better than Whorl of the Depths. Similar story for Pillar of Nirn, it's a decent set, but overrated on mag builds because of the 2pc Max Stamina. IMO Advancing Yokeda makes the best secondary set, assuming you can use daggers and stay in melee, and run it on weapon/jewelry to avoid heavy armor. Kinras may be stronger on a dummy, but ends up worse in group content since you'll already be getting some Major Berserk from an ally synergizing your Storm Atronach.

Stam Sorc is definitely better for a couple reasons. They benefit from the 8% max stamina on Bound Armaments. They get the benefit of every set bonus on Relequen and Pillar. They also don't need to use any crit damage CP since 6 medium armor will get a Sorcerer to the crit damage cap, enabling the use of Exploiter CP. Medium armor also gives more raw damage, since 2% weapon damage per piece is superior to 1% crit from light armor. Depending on sets, I'd recommend using as many pieces of medium armor as possible without causing sustain issues. If you have more than 2 pieces medium then Exploiter should beat Fighting Finesse or Backstabber.