The tree went up yesterday, and it was put on a lamp module set to the same codes as our other Christmas decorations, which normally run about ½ intensity. The tree exhibits the same flickering effect reported earlier with some Insteon wall switches.
Some background: The family room receptacles are all on the same circuit. The Ocelot interfaces to the powerline through a XTB-II, which is also in the family room at this time for convenient testing. We have not seen this effect with two other lamp modules on that same circuit
The inductance in the run down to the distribution panel reduces the load on the XTB-II, allowing the signal in the family room to be almost 30Vpp. When coupled into our distribution panel, the heavier load reduces the XTB-II output to about 20Vpp, but that falls off as the signals propagate away from the distribution panel.
Apparently a 30Vpp X10 burst is sufficient to couple into the lamp module's triac, causing it to trigger full-on for those half cycles of the AC power. This causes flicker in sync with each X10 transmission. Actually, it's kind of neat because I can see whenever the Ocelot is sending out a command. The effect was most evident last night as the module was stepped down to max dim.
All three lamp modules exhibit the same characteristic with that heavy load. None of the modules flicker at all with a dimmed 75W table-lamp load, even at the same receptacle. The lamp modules are from various eras.
I thought I would share this observation in case anyone else experiences something similar.