Hi idbl_fanatic.
the simple answer is yes, any HC is available to use and setup in all your macros and timers to work together, on one system I am using so far 7 HC, they do say to stay away from A and M and for sum P. These are the basic of X10 spelled out here http://kbase.x10.com/wiki/X10_Basics, all the info here at the X10 wiki Kbase and this Forum help me out to better understand basics of x10. Trial and error has worked very well for me too, just don't forget to save before the next step.
Ok cool...................next question, I have a universal remote set up to work through my IR543 (which is set to HC "C") in the settings of the universal remote, I have the options to switch house codes, and then also just like Light 1, 2, 3, etc.
So would I set it up so that it would switch to House G then Light 1 to turn on Module G1? will that work through the IR543?
PS, the remote is a Harmony 880