I've used both and currently using CandCNC.
My first machine used the Probotix where I had to wire everything myself. It was pretty solid and worked very well. It was ok to do but then I came across CandCNC.
CandCNC makes an AWESOME unit! I've spoken to Tom many a times. He uses his products on multiple machines. He has a forum that has constant traffic and he answers pretty much all the questions given. He knows his stuff very well. If you want something that's ready to go and can answer your questions from start to finish and can tell you why your torch won't fire, Tom @ CandCNC. They do TORCH! You can't go wrong with Tom.
I can't say anything negative about Probotix. They got me started at what I considered to be reasonable price. I even spoke with the owner and he was knowledgeable and new his stuff.
I went with Tom for many reasons, he lives in Texas (where I live) and he has this posted on his website:
DESIGNED, MANUFACTURED, TESTED, SHIPPED AND SUPPORTED IN THE USA
On top of all this, CandCnC was plug and play, provides Mach 3 screens with the stuff. I didn't feel like messing with wiring and such when I went to my 2nd much larger machine.