In addition to Apple's own discussion groups, you can also try the forums at MacNN. XLR8YourMac also has an excellent hardware forum, but unfortunately they haven't accepted new registrations in ages.
Regarding the XLR8YourMac forum, Mike (the site owner) will allow you to use the "BLF" guest login if you e-mail him about it. He'll provide the terms and conditions for using it in his reply, but it may take him a few days to get back to you about it.
There is some good information to be found in the "Macintosh Achaia" section of the Ars OpenForum at Ars Technica.
I was hesitant to suggest dealmac, since it has become exceedingly difficult to separate the wheat from the chaff. Two or three years ago, they would have been my top recommendation, but the boards are a disgrace these days.