One example, referring to someones earlier comments, of where the sum of a bikes dimensions may not equate to the obvious defining features is the Nicolai AC29. Twentynineinches did a longish test on one and loved it, rating it one of the best of 2011, this with a 72deg. head angle. It does however have long stays at 463mm, many are coming in at 447ish with offset seat tubes to allow for the short stays and avoid tyres striking seat tubes with 70.5-72 angles, others more like 553 with 69ish deg Head angles, more descent oriented.
I would offer that a 120mm 29er, especially with big tyres, will ‘feel’ more like a 140-150mm 26″ bike and the latest crop of 140 forked bikes will be more like having a 150-160 forked 26″ bike up front.
I also think there is quite a difference between manualling and popping the front to get over trail obstacles or lifting it on climbs. I tend to do the latter, mostly cos I’m crap at the former 🙂