Model numbering seems to be almost random. From what I've seen, I'm guessing 1000 series are basically 900 series but in a complete unit (900 series have separate display/control panels). The big problem with comparing models, is every spec sheet seems to be worded, laid out, and translated differently, so comparisons are hard to do.

I've had an email back from CNCMakers, and they've recommended the GSK218MC series, however as standard it only does a max of 3-axis simultaneously I.e it can only move 3 axis at any one time - I had to email them it clarify that.
I'm waiting to hear back.

I've also emailed Newkye to see what they recommend.

CNCMakers/GSK call the break out boards De-concentrators, and they have the option of basic ones that simply convert the 3 25-pin D connectors to screw terminals, as well as an output board with relays.