Now, we have firmware for 850/950 series.
http://www.pioneer.eu/files/support/AVIC-F50BT/AVIC-Fx50BT_Ver1.030000.zip
Bad News:
We need new testmode.key file. Testmode.key from 920-930-940 cannot work, other content and may be other encryption (?)
Good News:
We can decompile PLT file with Remaker_WinCE5 utility
We can extract NEvenWatcher.exe and other (Navi.exe, Hmimanager.exe, Av.exe, Download.exe and new app AppManager.exe) form PLT
We can decompile registry (in attach)
default.rar