I did hear back from Smithy this time. My email even made it up the food chain! Not only did I get a response, I got an explanation! I don't completely understand what they mean by hand-fitted to each machine, it seems to me that something ought to be precision made... like the ways. So one saddle ought to fit another machine because the ways are all alike. They did offer to sell me the parts to assemble and install an XL cross slide. It's a bit large of a price tag, but it's not the difference between the machines. Plus it's a piecemeal offering. Not assembled or anything, so I'll be putting it together myself. I'll update this thread as it seems appropriate.
ps. I'm still open to other suggestions!