Thanks for the replies! I had a thought (this rarely happens).
I've played with that same McDermott almost exclusively for the last decade and a half. I'm sure the extended pro taper (thanks for clearing that up) has quite a bit of deflection that I've just naturally adjusted to over the years.
Cut to yesterday when I'm shooting with a 12mm Schon with a much stronger taper, I'm rattling shots and I just don't feel as comfortable. I think that maybe that shaft has less deflection, so may just be throwing me off that little bit.
Now, I wonder if I should just adjust to it, get the Schon shaft retapered, or get a new low deflection shaft with the taper I like and focus on adjusting to that...
Decisions.. I've been reading about low deflection shafts, and it sounds like the adjustment may be more than I anticipated.