I've been riding my HT exclusively for the last 12 months instead of my full susser. I'm having as much fun, perhaps even more.
I'm clearly not as fast on the rough stuff, since those on F/S'ers start to open gaps out on choppy stuff, but it feels like I'm going as fast. Its a far more communicative ride which I think is more rewarding than straight out blast-through-everything speed you can achieve on a full susser.
I'm alot fitter for this coming summer, so I dare say I may find the summer more rough than last year, since I'm capable of more speed for longer periods now, which will make it feel rough for longer in the dry.
I'm unlikely to ever get rid of my full-susser – its my do everything, go anywhere bike for the bigger and wilder places of this world, but for much of my local riding, it just stays in the garage these days.