I never tried a 27.5"...no, actually I did try my wife's bike but that one has other challenges. But I love the 29"s...I road tested the Fug in temporary assembled configuration (I still need to bleed the brakes for good and cut the extra dropper post and shifter cables) and it was...amazing! I tested it going uphill on my street (Cupsaw Ave) and I could not believe how well it pedals, I was on the highest gear all the time and didn't even realized it. It may have to do with the fact that I installed a 28T upfront...Standing on the pedals feels great as opposed to the K2 where it felt...well, I just couldn't do it. The weird fact is that in spite of the seat being at the same height as the K2 I feel so much more 'in' the bike as opposed to being 'on top' of the bike, if that even makes sense. Weird looking at those huge wheels from atop!