I can't really weigh in on all the changes, as I usually just "compensate" for what I can't do. Other than the DX9 port, I haven't really kept track. Player1 said in chat: "everything in vp is a workaround. When you understand that, you will have mastered vp". For the record, I came in about when vp9 came out.
I haven't messed with vp10 much, other than so see what a table looks like. It looks nice, but it looks more "fake" to me. Like future pinball. Besides, like I said before, I have almost 700 tables set up in vp9. I'm not going to redo my entire setup.
A shame about that developer (Muskete?). I see his name periodically at the "dark side" (VPU).