Hi Roger
The G-series are definitely one of the best compacts when it comes to manual control, and yes, if the size makes the difference in bringing your camera or not, then a DSLR loses. But only on that criteria ;-)
Today, a beginner DSLR can be super cheap. There has never been a better time to buy a DSLR. Better yet, get a used one. Very easy to get a bargain, because everybody wants a mirrorless now.
@Ian:
It's probably best to mix and match. Bring the DSLR when creative motivation is high, bring P&S for the rest.
I would practice getting everything right when handling the DSLR.
Give yourself some challenges. Look at other peoples work, and when you see a picture that you wouldn't be able to shoot in auto mode, try and figure out how to shoot that same type of picture in manual mode. A hint…a lot of difficult shots require a tripod… I would actually go so far to say, that a tripod is essential for learning photography.
When using the P&S, i'd focus only on composition. Composition is everything!(auto-mode is good enough for 90 percent of all shots IMO (simplified). Practice moving your body to get the best shot, instead of using the zoom – and get down and dirty!
@Bob: If fallen in love with DSLR once, everything else is a compromise.