I fly out of YYZ in ERJ 145s all the time. I have a "salsa cabin trolley" Rimowa, which *will* fit in the overheads.
http://www.luggageonline.com/product...oduct_ID=17514
It is the carry on, that meets IATA specs. 50% of the time the check-in attendants tag the bag, but I just carry it on. It fits best if you slip it in wheels up. I have yet to find a plane where this bag would not fit in the overhead.
Will