Hi Dom, good question and simple answer, imho.
Unless there is a feature you really, really need (and I’d be curious what that would be looking at the available features on current controllers now) and that you know will be on a controller coming out in a few months (after being launched at a fair or tradeshow for example), then I’d wait a few months.
In all other cases, figure out what your workflow is, what software fits you and your workflow best. Determine budget and make a shortlist of the controllers that fit your software, workflow and budget. Try getting your hands on the shortlisted controllers to have an actual feel. Then pick the one you like best.
There will be new gear coming out every year or even sooner. But if you keep waiting for what MIGHT be in the next model, you’ll end up never buying anything.
My advice, go with the SX, which is a very nice a pro-level controller, and get cooking. One thing with new technology is that it usually has some odd bugs and “undocumented features”. I’d go with proven technology in your case.
Hope that helps.
Greetinx.