I have T5p.2 and treble is spot on for me, way more balanced then most of Beyers that i heard (warm/balance). Don't know if it is my cans or my hearing

Overall they sound very very close to each other, 3rd gen drivers are tiny bit more capable then 2nd imo but the tuning is achieved through front dampening of the driver. Because of that It has its typical characteristics which you might take in account. Highs - vocals are a bit less pronounce and a bit more laid back as far as I remember but again, difference is not that huge. I would say its very margin. From what you are saying , 3rd gen might be a good direction. Design and build is superior to 2nd gen. Get yourself 3rd on Amazon and decide by yourself.