That would make it doable and if the fares are cheaper many would consider it. But unless you're staying on the south shore or possibly east of the J-C bridge it wouldn't be anyone's first choice on the basis of convenience. Even for a seasoned metro user that's at least a change (and the least convenient change in the system) plus a bus. Doable but a pain with bags and a pain during rush hour.

But the record shows most people choose on price, not convenience, so "doable" is probably enough.