Steve,
well.. I've got some 20+ years old Velbon stuff I mostly leave at home due to weight. So first of all, I'm looking for a new lightweight tripod and a ball head for general purpose - and, as you write, with a budget modifier. I just wan't to add the possibility of turning it upside down because it - as you also write - makes it more versatile.
Yes, I noticed that compatibility is relative
Thats why I'm also looking for a ball head with the option of selecting my own preferred QR clamp. I might choose to go for a rail and L bracket instead of the multi-row pan head after reading the input here. I also like to do macro, and a rail might be a good investment.
I think shooting panos has become more interresting with the good stitching software that has become available. I started by trying it hand held and then began reading on the subject. Compared to the setup you have I guess the multi-row pano head I've considered isn't expensive, but I agree that it might end up in a box in the closet because it's not that versatile and also large to carry around.