new build opinions required

[JAZZCNC]

am going for duel x motors, so heres my first question.

There now seems to be nema23 and nema24 motors, with the latter having more power eg
4 Axis Nema24 Stepper Motor 567oz-in CNC Controller Kit With Display And Keypad | eBay

so, is it worth the extra for the nema 24s, or is there something am not seeing ?

YES your not seeing plenty.?

First the only difference between Nema 23 & 24 is physical outer Dim 23=57mm 24=60mm both have the same Bolt centres so both can be used on same mount.

The Difference you'll be seeing between them is Holding torque, Probably 3.1Nm and 4Nm.
Now the thing you don't realise is that what's important is the Inductance rating and often the larger 4Nm motors have much higher inductance than the lower 3.1Nm and this means they don't perform has good.
Now the Motors Eddy linked to seem quite Low inductance for 4Nm if that is indeed true.?? But most of the 4nm Chinese motors I've encountered have been quite High and IME the slightly lower 3.1Nm motors perform much better.

Now it seems to me your Rushing and not really knowing what your buying or what Mass you have to move.? This is a recipe for disaster and you will end up buying the wrong stuff if your not careful.!

The Kit you linked to is a prime example, it's Rubbish and completely wrong for your needs. The Drives are Rubbish junk, The PSU is way to Low voltage at 36V for those motors you'll end up with a very low performing machine. Thou this won't be too much of a problem thou has the drives will probably have died in short time so it won't be going anywhere.!!

Honestly I'm not just being Negative or pulling down but please take a Step back put a foot on the brakes and assess what you need better otherwise you'll regret it and waste shit load of money.

I'll PM you my number if you want to ring me and I'll try to help.