@wumple
Hey so I just upgraded to an M9 from an X1 so as you know I was quite pissed with the implementation of the terrible protocol that is MTP. The workaround that I have, if you can just buy a microsd to USB adapter for your computer and sync it that way (unless you already have a built in card reader). as long as it is formatted for the Fiio, the computer doesn't know the difference and will sync.
I did this fairly easy since I just used the sd card from my X1 for my M9. Just make sure that the M9 is completely powered off when you take out the sd card, and make sure you don't power it back on until the card is all the way plugged back into the M9. Otherwise, the m9 won't recognize the card and will want to update all the songs again, which takes hours (if you have 17000 like me).
Like i said it is a work around, and probably the best option, since this is a MTP issue and not a Fiio issue that we could ask them to implement in future firmware. Only downside is forgetting to put your SD card back in the M9 before you go to work for the day!