interesting... I had a space navigator (which seems like mostly the same thing as space mouse) years ago (used with AD10?? AD11?) when I worked in a company that had a lot of mechanical engineers doing 3D CAD in Solidworks and very tiny electronics team, so a space mouse was a standard part of an "engineers PC" there.
I kind of liked playing with it, but I never found much use for it with Altium. It was amazing for positioning and spinning a 3D board view around, and very cool for grabbing some progress "glamour shots" of a board quickly, but I don't spend that much of my day doing that.
Now I want to see what it's like for normal zoom/pan/scroll.... I never even tried it for that when I had it.... But it'd be useful to be able to pan about when the mouse is already active (like, dragging something). I can already zoom in and out while dragging with the good old page up/page down buttons, but needing to zoom out then in while dragging parts around to replace a simple workspace pan is a bit blah.
The main thing this discussion has made me want is a numpad keyboard to the left of my normal keyboard.... that would save a lot of left arm movement.
As for what mouse I would recommend.... Really - get something you like the size and feel of and use it. chances are it's fine. you roll the mouse, the cursor moves. you click the button, button click events get dispatched, it's all good, as long as you don't have a ball mouse full of fluff or an old first gen optical mouse on an incompatible surface.
For years I used to stick with basic USB professional and gaming mice with laser sensors... One day, needing a more mobile solution to match a CAD laptop that I was travelling a lot with, I got my first wireless mouse. I went with a microsoft BT mouse. I wasn't sure what to expect with Altium, but in my experience even this is actually OK for use with Altium, the batteries last maybe 6 months or so of daily use? It *can* be a bit laggy - seems related to other radio interference... but that's relatively rare. Most of the time it does everything I want and doesn't annoy me. The occasional lagginess is traded off for convenience and usability anywhere... when my last wired mouse cable went intermittent, I didn't replace it and the BT mouse came out of the laptop bag onto the office desk and became my daily driver.
At some point I'll probably get a new USB connected desk mouse again, I guess.. looking at the 3dx site, they have a "cad" mouse that looks pretty good, and is hopefully solid and well made, and not just an expensive logitech rebrand.