I don't see 30-amp as a problem. It's only dodgy when both airs are going full blast and we want to use the microwave at the same time. The energy management system does a decent job, but I still pop a breaker now and then. Overall, I'm satisfied with it.
It looks like the Vista line has been upgraded a bit. When I was looking for our '09 35J, the Vista looked very entry-level. I'm not as familiar with the Coachman line, but what you describe sounds like it's a little higher trim line than the Vista, so that might be a factor for you, but if the service center and the floorplan are your pain/pleasure points, you may be a lot happier with the Vista.
I think you're talking about low-point drains in the freshwater system? I think all of the Winnies have a tank drain valve, but you're right, mine doesn't have drains anywhere else in the lines. I haven't needed them. Mine has a suction hose at the pump to pull antifreeze right out of the jug. The only gotcha I've run into was with the hot water bypass. If you follow the owners manual directions, you'll end up with no protection between the bypass valve and the tank. Ask me how I know.