For me, my BIGGEST problems with infinite RR's has been twofold!
Firstly, though I have no problem with infinite movement on RR's, I feel that it could be tweaked to make it a little less....'all powerful'! There are two possible ways to do this. One is to make it that if you enter a city from a railroad square-you use up either 1 MP or ALL MP's (to represent disembarkment, etc, from the rail transport)! The second is that, if a unit ends its movement on a RR square, it may not initiate an attack on another unit, only defend against attack!
My other problem with infinite RR is that it makes industrial and modern age naval units way too weak, in movement terms, by comparison! This could be solved, as has been suggested elsewhere, by giving naval units a 'rebasing' ability between friendly cities that have the appropriate improvement! In addition, if you added a 'naval base' terrain improvement, which would function in a similar fashion to an airbase, then naval units would have an ability to move very rapidly within their wn territory-whilst still retaining the very important, strategic element of naval combat!
If either, or better yet, both of these suggestions were implemented into the game (either C3:C, or a future patch/XP) then I for one would abandon any call for removing infinite RR from the game!!
Yours,
Aussie_Lurker.