Hi, I'm on my second 29er - an Astrix Monk, and loving it. London based but riding mainly the Downs, Chilterns and Surrey Hills. My first foray, an On-One, was a real revelation - at 6'5" it was the first mountain bike I felt properly comfortable on. 29ers win out for comfort and control on most stuff I've ridden. And speed too - only my second ride on the singlespeed inbred and I was keeping up with a guy on an orange patriot down twisty and rooty Golden Birdies trail. That was enough to convince me.
Jump in - you wont regret it!
James