As for updates, I've heard some people buy an X1 + VPM just to use the thing in gauge mode.
I've actually found it completely unnecessary to put the thing in gauge mode. The VPM decompression information is so inoffensive that I let it run, and from time to time, peer curiously at it to see what it is doing. Since the computer will not lock you out, even if you don't follow its recommendations, there really is no penalty to letting VPM run. I was fascinated to see, last weekend, that despite the fact that I never gas switched the computer (so it thought I did the whole dives on 25/25) I cleared VPM's deco obligation before I surfaced. This was some interesting information on how conservative the assumptions that RD makes really are, at least for dives in the T1 range.