Im pretty much convinced that for the classic version of the game nearly all the great players were Hasbro CD players under Spring42. I understand the rules and some of the glitch made the game different I also understand that some purist didnt even want to try the CD version after hearing some of the glitches (we used to call the game Hasblow) but on the long run playing online just allow you to play way more game and against stronger players and against different plans/tactics than you could ever find live. Thinking your a good player because you can beat all your friend is a bit like being the best at chess in your high school. None of the pbem or the other leagues (Warzone or Axis and Allies Alliance maybe im not sure) I have played against were close to the caliber of the Spring42 players. Its a bit like online poker vs live poker, its not really close at all.
For the others version I have no reason to think that it would be different. Anwyaa if your very good you should have aat least some curiosity of playing against someone online no ?