Hi,
Welcome to the world of the JV-series synths. I own a JV-2080. While I didn't notice the midi timing as I was playing it in the store and listening to the sounds, I did notice it once I got home and began sequencing with it. The timing is quite bad. I like many of the sounds but the timing is driving me up the wall. Unfortunately, I need it to get some work done at the moment and can't afford to buy something else until I sell it. I will be sampling some of the sounds from it over the next few months and then I'll probably sell it. It's too bad.
Oh well, for any recording, I simply record each part to my hard drive one at a time. Time consuming, yes, but the timing is not as bad. I hope that Roland fixed this on the new XV synths (are they really that new? - they simply rehashed pretty much the same thing, gave it some better fx and a few more sounds and that's it). Because of the timing problems on the current JV's, I won't be buying one of the new XV's.
Fernando