Interested in a large version for dual battery. If it could also feature the 2.5mm charging connector to spare the USB port would be totally awesome.

If you can't have the nice springs to connect to the test pads, I'd be fine with wires that can be soldered. In fact, it could be even better- easier for you and easier for the modders.

BTW, another idea: what about recessed conducting pads, like on dect phones cradles?