Good question
Once rooted on ICS, you must install safestrap to install roms. The safestrap version you would be installing i believe is 3.04 (ICS version) The only Jellybean based roms you can install would be the AOSP, CM10,AOKP, or Dhackers Kill Rom for Droid Razr ICS kernel.
If you try to install those roms for the Droid Razrs on the jellybean kernel or the stock Moto Jellybean upgrade, it will crash or bootloop.
Safestrap relies on internal device memory. So, after you install safestrap. Make sure you clean your stock rom by deleting all the apps you installed. If you dont, you wont have room to install roms or any room for the other roms to install apps. Safestrap does not currently support external memory use for partitioning like sdcards (mainly because we would need high capacity/high class sdcards to support the feature)