In case you use Midi-OX for sysex dumps, one important aspect of the upgrade process is to correctly configure Midi-OX buffers.
Go to options/ Configure buffers
Set Low Level Input Buffers with:
Size: 32765
Num: 32
Set Low Level Output Buffers:
Size: 128
Num: 32
Run a “dry” sysex dump before connecting the Midi cable to your P6 Midi In and make sure the operation will finish. In case it won’t finish, you are in luck you did not connect your P6.
Hope this will solve a lot of headache.

Cheers,
Alec