I'm pretty much on the fence with this as well Molly, but experts with a vested interest are suspect to begin with. In Australia, 'company experts' said for years that asbestos was harmless, yeah right, so I will do my own research and make up my own mind I think.
Cell Phone towers are omni directional as with most wireless network antennas, this is better than uni directional or yagi antennas as far as signal strength and signal loss are concerned. I had the choice of yagi or omni when putting up my network between buildings at work, and chose omni for the fact that the signal strength is less and the frequency of the signal is less and spread over a greater area.