I use the hobby cnc board. I soldered it together and the only problem I had was with the 6 pin connectors. I switched from those to terminal blocks and have had no problems at all. I had almost no experience with pcb's before I did this project.
I run the 125oz-in with a 35vdc power supply. Turbocnc. I can rapid move near 40 ipm with no problems, I usually feed at around 20 ipm.
Dave does not recomend a larger system then his design, but I have had no problems with my setup. You can see some pics at my website or the thread in this forum:
http://www.cnczone.com/forums/showthread.php?t=694
Bill