The 305 (I have one) does indeed have something sort of like a "map." It's so pointless that perhaps it is incorrect to refer to it as a map. There is a screen that has some stupid track of where you've been. It isn't good for anything I can figure out. I wonder if that's what was left off the 500. I wouldn't miss it.
I'd love to hear how you use training partner. I've read the directions several times, but I can't figure out how to make it useful. I'd have thought by now some guru would have a blog entry on Training Partner best practices, but I haven't found it yet.
I'd love a 705, and the ability to download maps (like century or double century routes) so as to avoid teh dreaded wrong turn.