TL;DR - Wear any of the "good" gear sets for your spec, and you'll be fine. ROTATIONROTATIONROTATION.

With everything getting kind of equalized lately you're at less risk than ever of your stuff becoming useless, actually.

Mother's Sorrow & Medusa might be getting recommended in seemingly everyone's builds lately, but they're not head & shoulders above everything else or anything like that. It's just that with crit being harder to stack than before, these sets are even more attractive because crit is still the strongest stat (maybe after penetration). Most sets are closer together in damage potential than ever now, so you can get away with whatever you like (within reason) and still be doing pretty good. Don't forget that many (most?) builds are catered toward posting impressive dummy numbers, but not necessarily great "real" performance.

If False God's & Burning Spellweave (or whatever your jam is) is still giving you good damage AND sustain & survivability in the content you run, then you're going to be disappointed when you switch over to MS + Medusa only to find you suddenly struggle with sustain and got ~3% more dps to show for it. Or even a dps loss, due to sustain issues or whatever. I've seen people complain about this a lot pretty much every time the meta shifts and they gold out new sets.

Unless you're truly hitting a ceiling on your personal performance (perfect rotation, weaving, etc.) then gear changes will often make marginal differences -- especially now, with the recent changes. And if you're that close to top-tier already, then you can kind of get away with running any gear you want, since your damage is likely already above like 90% of the player base. :P

Those precious few percentage points in damage difference between the best and the rest only really matter for score pushers, tbh. Groups clear vet HM trials with "good enough" sets all the time; it's more about player performance. Don't let YouTube or whatever fool you into thinking otherwise.