I just updated my JTV-59 from 1.9 to 2.0. After doing so I couldn't upload any new tones to the guitar. Depending on what software I tried I would get a different error. If I tried the workbench I'd get a MIDI timeout or disconnect and if I tried workbench HD I'd get an exception (and work after downloading my guitar's patches all the tone names would have a "?").
I luckily have different computers and operating systems available to me from several flavors of Linux, to Windows and OSX (the latter being the one I use mainly) so I can easily test my setup under different conditions. Unfortunately my results were the same under Windows and OSX.
After many wasted hours and several Google searches I finally gave up and downgraded to 1.9 and everything worked perfectly again: I could upload and download tones without a single problem.
So now I'm left wondering why would Line 6 release a firmware that is clearly not mature enough for production use. I LOVE my JTV and will continue to use it as I find it's an incredibly versatile tool. Still, when I see beta software released into the wild -like the 2.0 firmware- it makes me think that some manager at Line 6's QA team is falling asleep.
Just writing down my thoughts...