Actually there is not difference between 1.5 and 3.5 by player skill, also I would like to admit that at 7s players aren't much smarter or better(probably not many gonna agree with me), on both 1.5, 3.5, 7 you gonna see busted irl reg's who are playing technicaly right game but still doing somewhere small mistakes what is the reason why they haven't moved up with their -2% roi and of course typical morons who are jaming every face card. It's up to you to play "right" poker with BM or not, just to admit that hypers are swingy as hell,so be ready to deal with -20bi++ swings.
Personally I play with 168bi roll at the moment and 90% of games is none turbo HU or turbo. I set a goal to move up next stake when I reach next level 80bi, but as you said you are going to play hypers I really suggest 100bi+
About tilt. Well, you can't do anything about it, I prefer theoretically play less tables move down stakes but in reality I'm making 2x longer sessions trying to get my loss money and it's not working most of the time. I'm really emotional and easy tilted guy so for me it's hard problem either. Just pray! maybe God will hear you and will give you some peace of sunday million final table.
Sorry about my English!