I know what you mean about being a perfectionist. I am too, yet I'm able to accept certain things (especially when I don't know about how to finish it properly in the first place).
Now that I'm looking up at the molding, I can see the line between the ceiling and the wall had I don't it your way would not be there! BUT since the painters will have to put a coat over the first coat anyway, they probably will be more professional about it and so just what you mentioned to do.
I start out being good to attention to detail but then I lose patience. I just noticed several spots in the kitchen were a touch of green is STILL showing through and I thought I got it all - so now I have to buy a new quart of paint just to do a few touch ups.
I'm learning by my mistakes, that's for sure.