Unfortunately, no. Once you flash any other rom including the Rogers rom, there's no going back to AT&T.
The whole point of flashing - at least for me - is to unbrand the phone, remove all the AT&T stuff and get the cool apps like Data Sense. You do lose the ability to tether but if you rarely or never use it, it's not a huge deal. If your main concern is to just get the GDR2/Amber update because the whole world is getting it and not you, then just hold out a little longer if you can.