My experience with 27.5 was on my hardtail which is 27.5+/29. I personally did not like the 27.5+ on the hardtail. Granted I was running 2.8 and later 3.0 at low pressures. I found that with the hardtail the tire pressure had to be spot on or the bike was squirrelly at low pressure and a bouncy house at higher pressure either way it was trying to kill me. I have no experience with 27.5 on a full squish but would think that a lower tire volume with longer travel for full squish would be better. The other factor that comes into play on full squish is that the higher the volume tire the more it messes with your suspension tune. I think it's really a personal preference to your riding style. I believe that smaller people my be more comfortable and able to get a better fit on 27.5 than on 29.