Bandwidth Place 2

I have the RT-N12 too and ionno, it seems functional to me... I used it before upgrading due to a sale on the N16 and ended up giving the N12 to my aunt+cousins who have no problem with it (DD-WRT on both routers). *shrug* I guess I didn't really have that much time with the N12 personally.

As for testing 5GHz out, I think a standard 'try and return' from a brick and mortar store will work.

From reading several reviews, it appears the N-12 should suite your needs just fine.

Of course, you'll need to flash it with DD-WRT but then again I don't know why you wouldn't.
If your worried about the wifi range / signal strength, it appears to be fine.