I spoke briefly with Neil at warkey, he confirmed that the 505 could be upgraded and that he was still hopeful of a January date for the 611. They had a 611 on the stand, looked just like the 511 but with a few small changes. I didn't look too closely. He also confirmed that the new software would be easily upgradable by the end user through the net.
He seemed like a good guy, I'm pretty sure I'll dust off my 505 and send it for the upgrade!
Rob