As I have recently purchased my second X-Lite (the first lasted donkeys years!) I can say the new one is of similar quality IMO and at 3kg possibly still the lightest of its type. I use mine for still water float/ledger fishing on various types of ground and it performs well with pretty good leg adjustment and sufficiently comfortable for sessions of around 5/7 hours. The feet have been altered slightly but still offer good support over soft ground.
However, I agree entirely with Binka in that you do need to be sure it offers the comfort level you require for your type of fishing. For example, I found that the back support sloped back a little too far for comfort (I suffer lower back/hip problems) so I have introduced a small packer between back frame and base which brings the back into a more vertical position - perfect for me as I now sit more upright, which is how I like to fish, and the back doesn't suffer!
Secondly, I have also introduced a covered foam cushion (5cm thick) which (for me) helps when sitting for long periods and can be carried within the chair frame when folded.
Lastly, I would suggest that if you are on the heavy side it is as well to try to 'lower' yourself into the thing rather than 'drop' into it, and I say this because a friend of some size found that the friction grip feet slid back into the frame if he plonked himself down from some height. He didn't break the chair, though!!
As others haver said; an excellent chair, reasonably priced IMO, and if looked after (eg wash the mud off the legs before retracting them!) will last many years......