Yes, a while back I had two sets of Naida Venture aids, one set SP and the other UP. Wearing each was very noticeably different. The UP aids were borderline hurtful though I got used to them. This is why I would like to see UP power in a size 13 battery hearing aid. Personally I would rather change batteries every 4-5 days and be comfortable than uncomfortable changing 675 batteries every couple weeks.
I believe these newest 675 battery Naida aids will be much better and comfortable than previous Naida aids. The Marvel Naida SP aids are also really nice if they have the power one needs.
Good luck with your new aids.