Bins on both side are the same size, and standard size rollaboards (14x20x9) can be stowed fore-and-aft in Y. In J, the same bags can be stowed wheels-in or handles-in over the right hand pairs of seats as the bins are deeper.

Here is a couple pictures of UA's Embraer 170, but should be very similar to Air Canada's E190. Notice the first row of coach, where the guy is exposed to the aisle, the bins over him on both sides are the same starting at that point, and can pretty easily take a rollaboard in the north-south orientation.

A bit hard to see, but the front cabin's overhead on the right side is significantly deeper, and can swallow a rollaboard probably as easily as an A320:

The front cabin bins on the left are probably even smaller then those on other regional jets, primarily good for jackets, purses, backpacks, ...etc.

My rough back of the envelop calculation seem to show that on a completely full E190, 65-70% of the passengers can find space for one rollaboard overhead per person.