Rikki, You can update the OS from ANY version, so it doesn't matter which version the one you buy has.
The MJ comes with limited styles, but thousands are readily available to install, including all the SD1 and SD1+ styles. Patterns and styles are the same thing in Ketron-speak.
Plug a USB cable from the PC to the MJ, and the MJ appears as another drive on your computer. You can transfer, audition, delete and arrange styles to your heart's content.
I found the MJ very easy to use in a live arranger setting, and the addition of the WAV, MP3 and Midi sliders is a great asset.
In this respect, the MJ offers real advantages over other modules for real-time arranger work.
Also, please remember that the MJ has a wonderfully-useful hard disk recorder that can record from all the modes at the same time if you want. You can even record external instruments via the line-ins.
DonM