FWIW, I've done 2 Centroid retrofits and used one for daily job shop type work. I found it to be far more useful and easy than any of the conventional controls (Brother, Siemens, Haas, Fadal, etc). I specifically chose the CNC10 because it was Linux based, now they are a hybrid setup with the frontend running on Windows and the backend running Linux (I believe). I appreciated the ability to use USB for transferring files. They had networking support, but I didn't set that up.
The one gotcha is they never supported resolvers, so you have to upgrade the motors or maybe find resolver to encoder convertors. I'd jump on a Centroid to retrofit my Fadal if they supported resolvers.
The irony is that my Fadal has rebuilt motors in it because they came off my Shizuoka when I did the Centroid retrofit...because they had resolvers.
Centroid integrated the DIY part of the biz (Ajax CNC) into their mainline offerings after finally seeing the light, so industrious people can pick the solution they need. The Acorn is a neat product that didn't exist before, it's a 3 axis step and direction controller that uses a Beagle Bone Black for the motion controller.
The reason this is special is that the BBB is a Linux single board computer that was designed in conjunction with TI. It has 2 realtime processors for doing motion control type jobs, in addition to the normal ARM processor every cellphone has. Linux runs on the ARM to provide high level stuff like network control and the PDU (I think that is the name) units are 32bit processors that get programmed by the ARM at startup. It's a unique design that is highly under-utilized in favor of the more popular Raspberry Pi. The BBB and rPi have their uses, but the BBB came with 4GB of storage on board and a pre-installed OS, starting it up and using it was dead simple and it was pretty powerful -- 1Ghz processor with 512MB of RAM, plus the PDUs, Ethernet, video, and 1 USB. When it was introduced the rPi was a 700Mhz single core with 512MB of RAM and was pretty limited in overall performance.