The other thing to consider: a high-gain antenna gets that way by discriminating against directions away from where it's pointed more so than low-gain antennas. Your closest channels should come in with a paper clip, so that's not an issue. However, the stations to the northeast may drop out completely when you aim an antenna like the XG-91 towards Buffalo.
Before you spend any money, please consult
this thread (if you haven't already) at DigitalHome to see what others in your area have done.