The MIDI timing issue was definitely there (at least on the JV2080). I owned a JV-2080 for a year. Shortly after getting it home, I noticed it and it would drive me bonkers at times.

Over time, I got used to it and took steps to compensate for it so it would be noticeable in my tracks. At the time, I sold another module to get it so it's not like I could return it to the store (or I would have). I now have the XV-5080 and it is better timing wise. There are some OS issues still on it but it is definitely better in terms of MIDI timing.

Fernando