It can be pretty great, but you really do need to treat it differently than you would on the grid!
For example: at night, making sure you don’t leave lights on, not running heavy loads like the microwave for very long, etc.
The good news is that as the old expensive equipment gets phased out, it gets easier and cheaper to DIY your off grid (or emergency backup) system!
That’s awesome, I’d love to get a system like that going for my generator. Good luck with that, if you end up doing it!
What’s the insulation situation in your house? I didn’t build mine and the previous owner who did used Styrofoam and cinder blocks so it’s a losing battle keeping it climate controlled 95% of the time (alongside no central ducts at all minus the chimney)