JohnKenn
Was wondering as also what if anything significant has changed.
AAS seems to be systematically going through their offerings and doing some kind of internal standardization/architecture-conversion. For example, we've got 64-bit versions of the two Strum instruments, but only for PC VST. What they just did for String Studio was probably a fairly major internal reworking to make it 64-bit across the board, although for PC users, the results don't look all that different. But they need to do this even though it's making quite a few PC users annoyed at seemingly marginal improvement. This is a far bigger deal for Mac owners of String Studio. They did this a little while back for Ultra Analog, and I think we can expect it for the Strums, maybe even Tassman at some point. I believe that Chromaphone, their most recent instrument, appeared based on the new architecture from day one and now they're working back through the earlier stuff.
But, hell, this is essentially a free upgrade with a mandatory purchase of an add-on library as part of the bargain. I don't get where some people are griping about AAS being out of touch with their user base, but that's just what's happening in a thread over on KVR.