Shadow World went to RM2/RMC when it became available (it may have been part of the impetus behind adopting its conventions). So yes, Shadow World is RMC compatible, even un-updated modules/guides. With the exception of the old lore-master series, which are RM1; main difference is that you have more skills & professions available.
You should note that SW does not really get behind the hybrid casters, but there are some options there. Amthor normally has them chose one of those realms, if you take this tact you need to adjust some of the profession costs to those of a pure user, but this is covered elsewhere.
But you can run the game anyway you want.