Actually the answer is really simple. (I assist in Artist relations for Gretsch Drums and help handle Jim's drumkits).
When they tour overseas, It would cost a lot of money in shipping and whatnot to send the same kit, (New Classic Vintage Glass) all over the world. So, to save money, they use back-line companies that store drum kits that we loan to them. So when a band goes overseas, all they have to do is have the back-line company closest to the venue send over a kit and all the band has to carry is the logo drumhead. Whenever Jim is local, he uses his regular New Classic kit. Hope this helps!!