Greg---No, I haven't seen it done. I think the few guys who want to add the GR/Rythmik Servo woofers to their panel speakers are thinking of going the OB route. But I thought for a guy who didn't want to spend that much, or didn't want the complexity of it, a simple substitution of the Servo in place of the ET woofer would be easy and effective. Both woofers are 8", and their diameter's are bound to be close enough to work, maybe with a little plumbers putty to insure the seal of the Servo 8". Then one would only need to run the two wire to the GR woofers through a small hole in the bass box of the ET-LFT8's (the hole could even be on the bottom of the bass bin so as to not be visible), and the plate amp could be put in a small box next to the bass bin. That's all it would take, and would be a big improvement to the speaker, I'm sure.