I hear ya Shawn.
I have a similar question. Does the motion
sensor on the floodlight send it's signal by
RF like the others, or does it send regular
X10 signals over the wiring? If it sends RF
signals like the regular PIR sensors, you
should have no trouble, since the security
systems only accept RF signals. I know that
for a fact because I asked tech support. On
the other hand, if the floodlight's motion
sensor sends the commands on the wiring,
there will be no way for the security system
to receive the signal. The security system
controller can only receive RF signals, like
from PIR motion sensors, or door/window
switches.
Maybe X10 Pro or Paul of LHS could answer
this one for certain?