My 8 years old projector died, so I got a new projector. After having it installed, I sadly discovered my X10 modules near that projector all quit working. I think that has something to do with the power supply from projector injected too much noise into power line.
I think these noise not only causing trouble to X10, but also to any control modules depends on PLC.
One way to address that is to have active filter at the output side of the module, and put all devices, including my new projector, behind those new PLC devices with built-in filter.
X10 has the engineering resources, the manufacture line, and the marketing channel. If they change their products to make improved hardware with open source firmware, I think they can gain a lot market share back. Arduino was nothing when it started, but they are huge now, because they specially made hardware for people to put on their own firmware. Also true for Linksys wifi router, that particular model selling strong for so many years, merely because the design allowing people to hack and modify the firmware.