Aside from repeated commands, I see no problems. It's 5 and 5 at my house with similar .ahx files. I use flags on the different machines differently. One machine handles the HVAC system with different flags and conditions.
After several attempts to zone BVC into a gated audio system (I even went as far as to zone stereo channels into 2 separate machines), I found it easier to use different machines. X10 Dispatcher, BVC and PCC run on these machines, as well as x10wavplayer. I use a combination of these programs, as different voices announce different functions.
The drawback is when a wireless transmitter is picked up by multiple machines -- you get duplicate PLC commands. This can be mitigated by setting the individual transceived housecodes on each cm15, or using a WGL receiver, or many other ways.
I personally don't mind the multiple commands, as the main problem comes from dimming lights with a handheld remote,which I seldom use, as I have BVC control a majority of the lighting. Multiple dim commands make it hard to set the lighting level to where you want it.