Bknot1,
I use
the Roland JX-305, which is identical to
the MC505 but is a keyboard and doesn't sport the D-Beam, but same soundset, same sequencer, same menus and so on. I love my board, it's the most essential piece of my studio. The sequencer is probably the best feature. Very easy to use, but can also get pretty deep with editing which is a huge plus. The sequencer only has 8 tracks including drums, but will still give you a huge sound. The track mute buttons are a huge plus as well.
The sound set is just okay. If you're coming from
a DR-660 you'll be happy with these sounds for a while but they will get old. The synth architecture in these is pretty limited so there is a finite number of sounds you'll be able to create (at least as far as I have found and I'm no expert). I personally used it on it's own at first (for about 6 months) but have since purchased quite a few modules and samplers that I sequence from the board. At this point I never use the presets from the 305, I have a couple original sounds I use for basses and synth leads and that's it.
I've never used the RM1X, but have heard some good and bad things about it. Lazi (in the Hip-Hop forum) uses one and I think he likes it, but he had mentioned he was having problems with some of the buttons on it. You may want to ask him about it.
User reviews will vary so take them with a grain of salt. I love my JX-305 but I've read reviews where people trashed it. I would suggest going to your local music store and trying both out. Only you will know what you will like.
BTW, this might have gotten more replies if it was posted in the Hip-Hop forum.
Good luck and I hope this helps.
Stray