I love offset. I use it all the time..
Usualy in the final stage of a mix, when I'm quite happy with how it sounds. (A mix I've done in envelope-mode, that is)
Then I jump into offset-mode just to nudge a few dB here and there, trying out different ideas (volume-wise) .. Since I've already mixed the track, only very subtle changes are made here.. and if I'm not happy with the result afterwards it's very easy to jump back to the mix I had (before entering the offset-mode) just by reseting the offset-faders.
It would be very nice if there was an easy way to see changes made in offset-mode, when in envelope-mode though, because it can (as most of you say) be a dangerous function. Especially if you're not working with it often and activates it by mistake =/
It would be great if we maybe could have two different color-schemes for envelope- and offset-mode. This would make it quite obvious that something's not as usual.. And also if we could see the offset-setting in envelope mode as well, next to the envelope-value.. Something like this (at the bottom of the fader):
-3.2 (+2)
..where the +2 in brackets is the offset-value.