Although I still haven't heard a thing from the seller of that ATK...
The Hipshot Bass X-tender and the strings arrived yesterday though, and unbelievably fast (posted on monday, and in on wednesday)! The X-tender is going on my G&L SB-2 - and I'll probably order a second one for my MIJ Fender '75 Jazz reissue, but I have yet to check which model I'll need.
I'll put it on as soon as possible (probably not before sunday though, as I won't be home much the next few days). I'm also really curious about the DR strings, I've never used those before (I usually play Elixir but currently also have D'Addario's on my fretless 5 and Ernie Balls on my G&L and Fender.
Many thanks go out to Andrew for the great initiative, and to him and the moderators for making this a great forum