Carl, everything I've found indicates a 10kg payload, I tried to download the manual to have a look but without success (something strange about their downloads). You're right in that it is an "old design" which I guess they tried to modernise to get more life out of the design. It is somewhat unique in that you can remove the Dec part of the mounting, attach a camera fitting, mount a camera and use it for basic tracking. Perhaps that's what it's referring to?
My normal thinking is to spend a bit more and get something bigger when buying something, which in this case would be an eq5 or 6, but then I start thinking that I'm getting away from the original idea and go full circle back to getting a lighter mount.
Given that these things (GTi) are in short supply, and I've found one, part of me thinks it's just meant to be so buy it!
