TJ Rubicon vs. TJ Sport or X?

I went and saw one of the two TJ Rubi's that I've found relatively locally yesterday. It was in great body and mechanical condition. The fact is, it was already lifted with new tires and wheels, and was ready to drive as is and I'm looking for a Rubi that I could make a project. I'm not looking for a rust heap or a money pit, but one that I could putter around with making it "mine". The TJR yesterday was great, but it was someone else's dream not mine.

Today I have another TJR to look at that has far less miles, but also appears to be in great shape too. The question will be if it is the base that I'm looking to upgrade or is it already upgraded more than I'm interested in.

This raises a question in my mind. I have been fully focused on getting a Rubi and have passed up tons of Sport and X models. Should I reconsider an X or Sport and use it as the platform to upgrade. Up until now, I wasn't planning on messing with axles, lockers, transfer cases, gears, etc. I assumed I would install a lift, bumpers, winch, service the engine (OPDA, PCM - as needed) replace belts and hoses as necessary, etc.

So I have two questions. Whats the big difference between the Sport and the X? How much effort to make the Sport or X have more of the performance characteristics of a Rubi (or close enough for some modest off roading)?

Bob