>>Yes, that works fine, but it's not a legal installation since it's *possible* to forget to throw the main switch.
My understanding is that opening the main breaker isolates the hot wires but doesn't isolate the neutral. Any voltages appearing on the neutral (like during an electrical fault) could still feed back to the grid.
I've considered doing the same thing, but don't want to take that chance. ;-)
It all depends if you wired the house right. I walk into places ready to catch fire, wiring wise, at a moments notice and they held up for 60 years. I knock of the main with everything else and slowly add things off the panel to start up. Got a $300 Harbor freight POS and it does just fine to heat and light.