Hi. I also shoot videos of trains. I have a Sony SR11 and an FX7. To answer your question, I can only tell you what I do. I shoot in 60i, with the SR11 1920x1280, and the FX7 at 1440x720. Both Cams shoot wonderful videos with great picture quality (and sound quality). What counts with anything moving is the frame rate; the faster the better. I can easily increase that with the FX7 (which I do when shooting moving trains), but cannot with the SR11. Either camcorder as they are does a great job producing a clear picture, excellent color, with minimal blurring (except on the very fast stuff with a static shot). As to 30p, I have no experience with that.
As a side, I edit my videos, burn them to DVD and sell them at local shows. I enjoy the creative aspect of it all, as well as the positive reviews I get from my customers. What do you shoot, and where do you shoot?