The E175 overhead bins will hold even a slightly oversized roller bag, so if you bag will fit in the sizing device (or is very close), you'll be fine. Overhead space is limited as roller bags go lengthwise, so if you're flying J or have status to get you in Zone 1 or 2, I'd say you'll be fine. Gate checks are quite common on this aircraft, but usually due to the capacity of the bins, rather than the dimensions of the bags themselves.

The CRJ-705/900 bins are terrible in comparison, so be thankful they aren't flying that on the ATL route any more.