Disclaimer: I'm a 3-railer. My opinion: the added noise from the center rail roller is negligible compared to other factors.
-Are you using the built-in sound systems? Turn them off! Try running your trains at slower, prototypical speeds. That will GREATLY reduce the noise from all sources.
-What kind of track are you using? Any of the "train set" track systems with a plastic base will be very noisy, I don't personally endorse them. Many say that solid rail is quieter. Atlas O makes 3-rail track with solid rail (if you can find it!) Atlas also makes 2-rail track, which might be even harder to obtain.
-What kind of roadbed do you have under the track? How is the track attached to the roadbed and/or to the platform? Screws through the roadbed conduct sound and vibration.
-How is your platform constructed? Do you have a sound-deadening layer such as Homasote or foam insulation between the track and the plywood base? Are there long, unsupported spans that act like a sounding board??
-Some 2-rail freight cars have plastic wheels. Some 3-rail freight cars also have plastic wheels (which i don't personally happen to like.) I like the sound of metal wheels and I think the track stays cleaner.
-Some drive systems (gears, motors, etc. ) are inherently noisier than others. Many 2- and 3-rail trains have similar drive systems. Personally I find die-cast locos quieter than brass. Both are available in 2- and 3-rail so the only difference is the roller. As battery technology improves, some folks are removing the roller and using on-board battery power, with remote control direct to the loco. I don't personally think this approach is ready for prime time, but you should be aware of it.
-What are the acoustics of your room? Hard, smooth walls? Ceiling tile / unfinished ceiling?
If the noise is what bothers you, see above. Remember also that 2-rail O-scale is still a compromise. The rails are still a scale 60" apart (which is wider than the prototype of 56.5") If you really want the track gauge to be proportionally correct, your options are Proto-48 (track gauge of 1.177" and very narrow wheel tread, demanding careful trackwork); or Q-scale (17/64" to the foot on 1.25" track.)
The main reason to switch would be if you're put off by the unrealistic appearance of the tall profile rail, and of course the center rail. I like trains and railroad operation. I'm really picky about a smooth and reliable loco mechanism. I like "train scapes" and want my trains to operate in an environment that conveys a sense of purpose. But Plasticville building kits and ground foam are about the limit of my modelling skill, so the center rail doesn't bother me. It's a highly personal decision, so do whatever makes you happy!
