I have a XC orientated HT – Kinesis Decade Versa II – and a 650b FS – Whyte T-103 Works – and enjoy both just in different ways.
My riding buddies are all quicker up hill than me, I’m heavy :-), but only one is quicker than me downhill. The quicker guy rides a 26″ Five and is one of those riders whose just fast everywhere. If I’m on the HT I’m usually 20 – 25 metres behind him on our longest singletrack descent and on the FS it’s more like 10 – 15 metres.
One of the biggest changes I’ve made to the HT is to put good quality, Maxxis Ardent 3C, tyres on it rather than the slightly ancient Panaracer ones I was running, this has increased my confidence in the HT’s grip and in particular corning speeds.
Both FS and HT get mud tyres in the winter but mostly ride the HT just due to the extra maintenance the FS takes in winter.