Thanks Keith. I have had mixed emotions on controller size and what controls to put where. I decided to go with the larger two-dial-controllers-in-one, because I liked the idea of being able to control two trains simultaneously from a single panel for things like consisting and yard operations. However I did not want to be limited to the two controllers, therefore my inclusion of the CAN bus that could really be used for any kind of peripheral... a wireless receiver, wired controllers like you are talking about, etc. I like the idea of having the master controller, input dials and booster all in one package for those folks with small layouts and limited needs, but yet providing a mechanism for future flexibility. After completing and testing, I plan to make my design and software free to all who are tinkerers and would like to have some flexible and powerful DCC control functionality without the exorbitant cost I have seen for similar setups.
One particular question I have wrestled with... Do any\most controllers give you the option to set a loco to a particular speed and direction and then select a different loco to manually control without affecting the operation of the first? Kind of a loco cruise control? This is the direction I am heading... allowing as many locos as the memory will hold to be directed simultaneously. This will of course requires a well-executed "emergency stop all" mechanism to avoid disasters.