loving mine – an OnOne Fatty.
Sold the Full Suss to fund improvements on the Fatty as was nor tiding it & hardly ride the old 26er at all now.
Now doing things on it that I hadn’t dreampt of before, eg just done the Lakeland 200 on it bike packing, 200km, 6500m up in 48 hours carrying all food, tent etc..
As for performance, it is faster in some areas (it loves cobble & rooty surfaces), Slower in others (very rocky down hills), allows you to ride where others struggle (bogs, beach snow).
climbing – I actually think they climb really well, especially where extra grip is required. Got a KOM the other day , Ok it was soft tussoky grass but still, dead chuffed, they can’t be that bad.
(don’t argue with Tazzy – you’ll never win – she (apparently) knows ……