Hey Konrad,
When Write automation is enabled you cannot be in offset mode
on the track that is write enabled.
In other words once you write enable a track to be automated, this takes it out of Offset mode for the track that is write enabled. this means that you will have some tracks in offset mode(the one that are not Write enabled) and some in automation mode.
I hope that helps clear things up a little. Once you get it you will see that it is a simple concept and yes it took me a while to really understand the benefits of having a Offset mode and Automation mode, So I really do understand the confusion
And to add, The Gain on
tracks are never in offset mode, because you cannot write Gain automation (which is different than clip gain automation) on tracks, I think that Buss gain will be in Offset mode (because you can write Buss gain automation)
I hope I haven't confused you more, but once I figured out it was a lot simpler that I made it out to be when I first used it, I think it is a great feature and have a hard time mixing with out it.
Another benefit for offset mode, it once I have everything sounding great but I am pushing the master buss to hard, I can go into Offset and select all tracks, hold Ctrl and lower everything at once while maintaining my gain stage, If I did this with gain my FX would be affected by not receiving as much signal.
@Beepster glad I could help, nice to meet you too.
If you have anymore questions feel free to ask, I might have an answer or at least be able to B.S. enough so it sounds like I know what I am talking about

.
Tom
Edit: to add when in Offset mode, Faders/Pots will not move.