It's pretty much exactly as j_m_ described. The Run-DMD in it's current state is not capable of handling individual colors on the HUB75 panels. I don't have all the data, but hardware wise it's doing a superb job handling, shuffling data and updating the animations even with all 16 shades without any hickups, but a full color solution would be too much for the current hardware.

Torbjörn (the creator and brain behind the Run-DMD) has said that it would be possible (in theory) to build a "true color" Run-DMD, but pricing wise that would cost probably the double, and I've not heard him talking about it in the last two years, so I would say it's probably not going to happen in the near future.

j_m_ has been a great partner in the last few years spreading the word of the Run-DMD in the USA. Shipping complete clocks from Sweden would have been impossible with the current postage rates, and I'm pretty sure I wouldn't have been able to build so many complete kits as he has done, so we're very thankful for all the work he's done for the Run-DMD and the community.