Here's some results of mine, i got mostly tens and a couple nines for signal strength using a PS3 engine in the lead, and nine PS2s following.
http://www.youtube.com/watch?v=kwMsgxqVSHM&feature=plcp
Couldn't get the camera to focus all that great. Ran tests with just a couple cars so there's a big gap. I have 150' mainline divided into four blocks using two TIU channels and two Lionel 180w bricks.