So, in a quick gut comparison, I bought the Active 75t and A/B'ed them over 20 mins in the BestBuy parking lot. (Got them on sale!
After updating the Active 75t firmware, calling my mom (my fav test subject) and listening to music/playing with the EQ - I came to the conclusion that I vastly prefer the fully sealing 75T immersive feeling than the semi-open 85t. Given the multipoint is there, the ANC and hearthrough (a much better way to introduce outside/ambient noise than the lack of isolation imho), I very quickly realized that even though neither of these are the endgame for me in SQ, I enjoy the bass delivery of the fully sealed 75T more, particularly for bass rumble and extension (after firmware update). The waterproof/exercisability is an added plus.
So, for me, the 75T won very quickly. I didn't do a lot of audio comparison regarding range, separation, detail etc, but the 75T were immediately more 'fun' and immersive for me with the bass, both things I look for esp if I will use them for exercise. Plus, smaller case! Smaller housing. Deeper seal.
If you want a song to compare bass extension, I quite like using the beat of this song to compare:
I am well aware this is not gonna be most of your cup of tea and make no claims that this is the best produced track ever - lol - no need to tell me
So I walked in and returned by 5 day old 85T, pocketed the $90 difference and haven't looked back at all. I agree that the 85T should not be viewed as a successor to the 75T but a separate style product. (Not sealing, is HUGE, in my experience, and I don't mean the tips, I mean the pass-through port on the 85T. (I ended up finding the smallest tips went the furthest in my ear but not having that passive isolation keeps me from being fully immersed).
Just my 2c obviously, but those of you on the fence bass-wise, I say get the Active 75T and save some $$$.