Ok....I may be really really late in the game for this one. I came to the BB world in November 2007. I came from Moto Q with corporate exchange. I switched companies and decided to only use my new BB for personal use. I knew that Hotmail was not the best option for BB. So I tested Gmail and Yahoo and ultimately went with Yahoo.
I just upgraded my wife to a Curve and found a link which I believe has solved the issues people have with Gmail. If I had known about this I probably would have went with Gmail back in November.
https://mail.google.com/support/bin/...y?answer=78882
Anyway, I hated the fact that you had to apply filters so the sent mail wouldn't be returned as new mail. Setting up Gmail this way keeps the message chain in good order and so far seems to be true 2-way sync and no annoying sent mail as new mail.
If this is really old news please go ahead and blast me for being a moron, but I was pretty excited about this. The only drawback, is that it is not as fast as a Gmail account that was setup without using this work around.