I've been using both for a few years as well now. I find the Charmoz ideal and have basically used them for about everything I've done in the last few years; from walking in Scotland to easy 4-5000m peaks. I've used them for winter climbs up to grade III, and they've been absolutely fine. Having said that, I've never used B3 boots, so don't know how it compares to that.
In reply to Moondancer: I have the Charmoz with Grivel Airtech 12s. Great combination. Not one crampon has popped off in 2 winters. Also very confortable and light boot. Again have taken up to winter III without problem.
In reply to JayPee630:
I too have used Charmoz boots with G12/G14s and climbed up to III/IV.
I love the Charmoz.Rock climbed up to S/HS in them.They were fine on the Papillons ridge (Aig Peigne).The only problem has been that I occasionally have started to feel the cold a little more if on a more severe/cold day.
Mine need re-soling, and do not know if this will be worthwhile.In the meantime I used Mont Blanc's due to the Charmoz tread going.I suspect that the tread does not last as long as on some boots.