Hora’s made my point for em I think.
I’ve ridden follow the dog on a 7″ freeride bike, lots of fun, but it was definatley fastest on a 100mm sub 25lb race full susser up the hills.
IMO (nearly) all bikes are (nearly) as fast as each other off road. If you dig out old coppies of dirt, the number of mentions the 1:04 track gets in relation to “this 4/5/6″ bike gets to within a second of the intense M1/M3/IH sunday/orange 222/223/224/etc” so from that its concludable that its 98.5% down to rider ability.
Thats not to say the 7″ bike isn’t easier, and therefore there are less of those moments where the bike just gets horrendously out of shape losing a couple of seconds, which is where IMO most of the time is made up. Also explains why some nichesters claim to be able to stick with DH bikes on the downs, its not because your awesome, its because on that particular section neither rider or bike is anywhere near their/its limit. Throw in a rocky chute into an off camber corner more reminicient of a north wales scee slope and the nichester will be left for dead (possibly litteraly).