peregina, bag chick:
I also fly Air Canada (not much choice where I am) and I've used the Aeronaut as my carry on item for the last 5 years. I've never had it weighed or been forced to check it in. I've never had a problem with flying on US carriers either, but Lufthansa can be very particular: one on international flight out, they did check the weights of all bags.
I used to carry my Brain Bag as my personal item, but as others, I suspect it really is too large. I've since switched to the ID messenger bag as my personal item. I now use a MacBook Air for travel - one of the best computer purchases I've ever made.