I was looking for a bike for similar needs to yours... I had a hard tail (GT Avalanche 0.0) and wanted a XC full susser for riding in Scotland...including the 7 Stanes, Laggan Wolftrax etc...
I bought a 2008 5.5.1 from Lex's (
www.lexs.co.uk) with a big discount. I'm amazed to say that I think it actually weighs pretty much the same as my GT... other folk have lifted them and couldnt really tell the difference... I have no problem (apart from my general winter lack of fitness!) in riding it all day, and whilst Im still getting used to it, the downs are so much easier than on my hardtail! I may not get down with any more skill, but I dont hurt so much at the end!
I wondered about 140 being too much but I'm not sure I really notice it, even coming from a 100 mm hardtail with cheap forks. I find the back end has much more traction than my GT had. I play with Propedal on and off and actually prefer it on most of the time, except possibly firetracks. You can also lock out the front forks on the firetrack uphills if you want to.
The cockpit is is noticeably shorter and I do notice the front end being a little higher than on the GT... I dont think this really makes it more difficult uphill though, especially given the extra traction, (ie I can still make it up the same ups, perhaps more easily now - so the extra traction seems to outweight the possibe negative of a slightly higher front) and the higher front does make it much better for the downs... you dont feel like youre teetering over the bars so much...
Seems quite versatile... and have felt able to book my first trip to BikeVillage in the Alps (wasnt sure I'd be able to handle it on the GT)... Now I think it will just be down to my own fitness whether I make it thorugh the week, rather than being down to the bike...!