the bins in y held my very full travelpro crew 7 (fits into the sizers as snug as it gets) a-ok sideways. takes a bit of maneuvering when it was stuffed but any other time it was fine. if you have a regulation carry on the bins are a non issue. the people who suffer are those who have oversize carry on. the j style bins on the 705 only existed in j because they protrude out of the roof onto what would be the y aisle. so i wouldn't count on bigger bins.
I have a regulation carry-on and it's often a struggle to get it in the bin and sometimes not possible. Have seen the same with others, sometimes slightly smaller bags as well.
It can at times be a question of angles, how full the bins are, etc, but either way, the bins are woefully inadequate. I don't remember the last time I took a CRA flight where there wasn't a bunch of baggage to gate check. (Yes, not an uncommon problem on other planes these days, but not quite as universal as on the CRAs, in my experience).