This is true. According to my SA at NM's in BH, the leather on the new GST is softer and more slouchy. She modeled it for me and, while it fit under the arm better, it lost its shape and looked really worn. Didn't like it and am very happy I bought my GST in summer from old stock!
I actually wish it was a little stiffer. Its not as structured as it seems. Mine is newer so I think the caviar is softer. Anyway it is a great bag. Im sure the backaches are caused more by whats put IN it rather than the bag itself.