I used to commute to work on a knackered 20year old steel racer that weighed 40lbs+, 17years+ ago and it was 20years old then. 17miles each way, used to claim for bus then train then bus fare as it was YTS lock the bike 1/2mile away, got away with it aswell :)
They were early model comps with two piece lower legs that hold together with the brake boss bolts. I didn't think my 29er had much more tham 60 mmm travel. I tested my full suss Whyte JW2, my Jamis 100mmm hardtail and my 29er round Cwm Carn and they all handled it fine, The 29er went through some of the rocks noticeably easier, however it wasn't very good out on natural terrain ripple bumps as there wasn't enough front suspnsion so I sold it intending some time in the future to get a 100mm version. It was much much much better through boggy welsh tracks. I remember leaving Danny Milner and Andy MaCandlish for dead on one bogtrot. I had to wait minutes for them. If I had to buy again from scratch I'd buy a 29er, no question. It's so much quicker in the winter, I also got up tracks that I either spun out on or had the front end lift with 26'' wheels. I'm 5' 8'' with 32'' legs and it fitted me fine