Forgive me as I'm fairly new to this game but I'm currently running Eclipse 1.3 (GB) and would like to try ICS. Would I be able to go back to Eclipse/GB if I'm not happy with the stock Verizon ICS?
Nope, you will only be able to run the stock "leaked" ICS. There are no alternative ROMs at this time for the leak and you can't go back to Gingerbread. Hashcode is working on CM9/ICS for the leak so AOKP would also follow soon after that...but as of now....nothing.