With the antenna tweaked, 49 should come in fairly clearly if you want to get the others. Before I installed my current antenna 49 was fuzzy, and I didn't really get any of the south Buffalo stations.

Re the preamplifier, I think it'll depend on the receiver. I've got a dual UHF antenna stack on a 44' tower with a strong preamp and my reception of Toronto stations is **super** strong - for instance my antennas are very directional and yet City-DT comes in almost ANYWHERE I aim them. Yes, you can overwhelm your receiver, however Toronto stations are fairly low power to start with so it may not be an issue.