Again, i know my opinion on a non tool changer 2 axis knee mill isn't always a popular one, but it was mostly in regards to the O.P.'s statement:
"I’m at a point now with my builds that I’d really like to start tinkering around with CNC machined parts. Mainly building custom triple clamps, instrument clusters, and other random one-off parts."
At my last job, when I had equal access to a fully tooled Vertical Machining Center (with a tool changer), a 2 axis proto trak AND a 3 axis proto trak, I chose to use the 2 axis knee mill every time for the one off stuff. He is wanting to do mostly custom one off stuff, and those are rarely feasible to do in a machining center. Especially the idea of walking away and working on something else. Anytime we did a first part on a VMC, you were watching that thing like a hawk with one hand on the rapid control and one on the feed hold. Granted, once you got past the first part, there was time for other things, but if your talking about one or two piece runs it doesn't make sense. Aside im assuming that we are leaving out the idea of 3d countoring, which i did very little of even on a vmc.
There is also things like triples, especially pointed out by the p.o.
Even when I did program the VMC to mill a profile of a part, it was still much more common to do secondary operations on a knee mill. especially when you are talking about having to set up for the pinch bolt. You now have 5 tools to set and program for one simple operation. Tap drill, clearance drill, counterbore, countersink and tap. That operation is a bunch quicker on a manual than setting up to do two pinch bolt holes on a cnc.
Even in the job shop we worked in, the 2 axis was an invaluable tool for one and two off stuff, or even just second ops on the parts coming off of the vmc.