Well, the G250s would actually fit my situation better. In fact, after reconsidering the G250s VS. the board from HobbyCNC, I now realize I have an old power supply that could be modified if I use the G250s. The supply is in a steel case with a fan on the back, and two sides of the case have large, finned heatsinks mounted. All the controller circuitry would fit inside the case, and the G250s could mount directly to the existing heatsinks (with appropriate insulators).
The thing is, this supply isn't a good fit for the HobbyCNC board. It was originally a commercial design specified at 13.8 VDC at roughly 40A. I inspected the transformer this evening, and its centertapped secondary measures about 33.5 VAC without a load. That means it can produce either 24 VDC using a full wave rectifier, or 47-48 VDC with a full wave bridge. The lower voltage isn't enough for either controller, but 48V is just right for the Geckos. That means this supply could narrow the cost difference for me between the two systems. Aside from that, it's been hangin' around the house for nearly 10 years. I've just been waiting for the chance to turn it into something useful.
Thanks for the tip on the Keling KL-DB25 BOB. $25 and it's even opto-isolated!