I personally find the Companions the high point of the RM series. Yes, I know there's a mad power creep. And yes, they do get awfully complicated at times, but if you have time, eBay is your friend. Go out there and get Companions I-VII along with Character/Arms/Spell Law. It's mad, and there's too much at times, but I love me some good old RM2 with hundreds of professions, including ones which, really, don't make any sense.
If you're sane, yeah, go with the prior posters. Me I'm sticking with RM2, the full set, until RMU comes along, which GREATLY improves the system IMO.