Oddly enough, I've just bought a 3 pack of Arduino Nano clones - 2 for use with EstlCAM and one as a spare (Nano essentially being a Uno but squeezed onto a much smaller board). This is to let me use a PC with USB port to drive my engraver and potentially my mill - and also EstlCAM controller doesn't have the limit on number of lines that Mach3 (free) has.
I'll probably also buy an EstlCAM licence for the CAM functionality.
Interesting things I did learn whilst searching for these, there are those out there who advertise what claims to be a Nano, but has a different version of the Atmel chip on board with less memory - check the listings very carefully. Luckily I spotted that and decided that for a whole £1 or so per board, I'd make sure to get the correct chip. Not sure if same issues exist for Uno.
Despite having the CH340 serial/usb chip in place of the FTDI chip, the boards I purchased worked flawlessly when I asked
EstlCAM to program the board.
Must admit I was using the latest EstlCAM beta, not the 'production' version. Looks like a lot of work has gone on in between. Might be worth trying a different build of EstlCAM to see if issue is with the program or the board.
When asking a question, I got very prompt response from Christian at EstlCAM - might be worth dropping him a line.