I traded in my MidJay Pro with SD40 expecting it is more stable/refined but sad to say, it has more issues than MJPro. I owned it for several months now and I'd say i'm leery to use it in gigs. Here are the issues i'm experiencing:

1) When you change style variations, frequently it will revert back to same variation (i.e. var A to var C it will revert back to var A)
2) The Registration screen frequently freeze, it won't scroll up/down that you can't able to select registration entries. You have to reboot the unit to be able to scroll again
3) The Recorder is unusable for me due to distortion, tin can quality and strange noises during recording
4) The registration won't memorize mic/harmonizer settings. I have to adjust it always as it is too loud or to low or incorrect harmony
5) When you re-save an SMF with piano sound, it will mess up the piano sustain setting
6) There are Registration entries that it takes forever to load
7) The majority of live style playing controls like intro, reintro, end, fill/break are screen-based. You lose all these controls if you're displaying text or pdf lyrics on the screen

In a nutshell, i regretted trading in my MJPro. I hope these issues will be address next OS update. Other than that, it's a great unit when it's working well and it's the only module arranger in its class in the market.
Just my 2 cents