I have a Voyage and that's a great ereader. I like to think of myself as a very principled person. My values go something like this: reading is most important and after that comes my principles and hopes for a better world, which is pretty much on par with my need to feed myself and pay rent.
I don't know that the Voyage is the right one for you but it just might be and letting principles keep you from having the best possible reading experience seems self defeating. Especially when the principles involved are somewhat vague. Ereaders aren't political statements.
As for syncing, I do that all the time. I get most of my ebooks from Amazon but I do get them from other sources as well and I sent them to Amazon in mobi format for conversion, they go into my library and I can download them to any Kindle or Kindle app (except, as mentioned, on the PC) and sync them. It makes reading them easier.
I also like Moon+ reader on my tablet now and then and sometimes I'll read a book with it and manually sync with my phone when I think I want to read while away. At first it was an experiment that I expected to fail because it would be a hassle but I've found that surprisingly easy. I'd do that more if I didn't get eyestrain from extended reading sessions on LCD. In fact that would be my preferred way to read. I like Moon+ a lot. I just wish they'd get rid of that silly + in their name.
Barry