I would say that X10 is stable, but far from bug free. The fact that there are updates speaks to that issue.
IMHO, X10 is an incomplete system. Largely I find the documentation inadequate and support for custom content non-existent. I will continue to play with X10. But with the lack of support and a product strategy that escapes me, I've started trying out other products.
As best I can tell, FPSC itself, is meant to provide the entertainment. For many here, that's exactly what they enjoy the most. I'm more focused on creating a product, and just don't see that happening anytime soon.
"I'm trying to find new ways to make this game more attractive." - Dennis Rodman