Your machine has such a small footprint and they are a better match for the hobby cnc boards power output. As the motors' inductance goes up they will go slower for the same amount of voltage. The larger motor had more inductance if I remember correctly.
I have absolutely no experience with the hobby cnc products other than what the website says. I am also not bashing them.
I would make sure that it will do what you want now and in the future by reading other stuff other than their website. Do a search on the zone and the like.
Does it have optioisloation to protect the computer?
Does it have mid band compensation, without which the motors will stall at a much lower speed reducing you machines usefullness?
Have other people had good luck with it?
Will it play well with your next machine or are you going to have to buy all new components, including motors again?
If you are going to convert an X2 size mill, which is not a large machine, and very popular, will this drive it?
I know money is tight, but I learned my lesson with my taig and the xylotex driver. It is a fine product and well supported, but it isn't gecko.
Just my 2 cents.
Mike
Warning: DIY CNC may cause extreme hair loss due to you pulling your hair out.