Tony_F,
Welcome to the forum.
To directly answer your question, current competing technologies include:
1) Insteon (backward compatible with X10) - Mixed powerline/RF communication protocol. Each Insteon module acts as a repeater to maintain signal level across the powerline. RF is used for coupling phases (unit to unit communication is via powerline).
2) Zwave - RF communication network
3) UPB - Powerline communication protocol - 40V signal level and lower frequency (high bit rate) improves signal to noise ration.
The above are arranged in the order of increasing price. Typical Insteon wall dimmers go for around $40. Z wave dimmers are around the same price but you'll need additional support hardware to program them. I've seen UPB dimmers for $50 to $70 each. Sorry, I don't know much about the support hardware for these.
Of the above, I have both Insteon and X10 units in my home. The Insteon protocol is far faster than the old X10 and offers many nice new features. It is be no means immune to noise. I use the same X10 filters and troubleshooting tools that I used with X10 20 years ago.
Smarthome put out a whitepaper a couple of years ago comparing the technologies. In general I'd say the comparison is valid. I'd take some of the conclusions with a grain of salt... The paper is located here:
Smarthome Insteon WhitepaperSo, to sum things up, we can provide alternate technologies, but we cannot provide a recommendation until we understand your requirements and price point. Any of the above technologies will likely cost you far more in dollars and time than fixing the noise in your existing X10 system. Add the fact that there really aren't any troubleshooting tools for the new systems and you may be better off with the system that you know and have worked with for years (at least in the near term).
I'm not trying to talk you out of anything, just trying to understand the end goal.
Boiler