So, the way it goes here is the RM2/RMClassic users are going to tell you to use it and the RMSS/RMFRP are going to tell you to use it.
I use a modified RMSS (with RM2 and my own stuff) to be fair... but, I think as a new user you DO NOT use RM2. Maybe use RM Classic or maybe use RMSS/RMFRP.
RM2 is not friendly to new users. It's not organized well and balance is out of whack if you use the wrong stuff. Being new you aren't going to know what 'the wrong stuff' is.
I am not sure if organization and balance issues were addressed in RM Classic, however, RMSS/RMFRP has much more material out than RM Classic. I can say, if the skill system being 'book keeping' is someones criticism for RMSS/RMFRP, just do away with categories and use specific skills providing them with 5% per rank instead of 3%. Problem (if such a minor issue is a problem for you) solved. Also, if you didn't find learning Pathfinder challenging, I don't see why you'd find Rolemaster all that challenging.
Essentially I use a mix of RM2 and RMSS with a tiny amount of RMFRP tossed in, so if you have questions about certain aspects of each fire away.