Well, I ended up doing the upgrade the other day.
As has been mentioned, HD500Edit etc all work fine.
There is an issue with the USB driver causing static like noise when recording, which I have created a support ticket for.
Fortunately I can just connect the XLR out from the HD500 in to the mic in on my Focusrite 2i2 and use that to record.
Hopefully we'll see a driver update soon which will sort it out.