On the 200DX, you'll have a lot less complexity and cost if you stay aircooled, and you'll have a more portable setup as well. If that interests you, I'd go with the CK Trimline 210 with flex-head and superflex cables. 200 amps @ 100% duty cycle A/C. It doesn't even cost all that much. And if you want the smaller WP9/20 cup style, you can get stubby collet body kits also. (That's what I have my torch set-up and use the most often, at the moment.) You shouldn't need anything but 1/16" and 3/32" tungsten diameters.

But yeah, I'd not worry about it too much, and just try out the WP26 to start with. It will get you up and running, at least.