I would recommend avoiding X10.
X10 uses radio frequency and "power line controls" protocols that were developed in the 1970s. They have done little to improve on the performance and reliability since then.
Its possible they have improved, but when I got into X10, the quality of their products was shady at best.…

What is it about your system that you're not happy about?
I think the first step is to figure out where the bottlenecks are (if any) and start working oon those first.