Toronto's landing charges are known to be huge and IATA are forever moaning about them. If globespan can make a go of it GTAA will be shuddering as they are in the middle of enormous terminal construction and suffering reduced shop sales due to carry-on rules.
Hamilton's historic problem for a lot of routes is that once people get on the QEW to go there they might keep going to Buffalo, but that's not a problem on UK/Ireland routes. NW's rumoured TA 757s ex DTW would also be an issue for catchment in the area southwest of HAM.