Yeah, recently learned about Capabilities. Followed few tutorials (unfortunately not updated) and with some tweaks got it to work.
Here is my code for reference - https://github.com/Oen44/RPG-Mod-MC
And here you have something about how to make one - http://jabelarminecraft.blogspot.com/p/minecraft-17x.html
The whole system is built with the idea that every block will be registered every time consistently. It is just a bad idea, diesieben07 would be able to explain this better than I could.
Override the method in the block class that have a IBlockState parameter.
There are down times on here as well as anywhere else. I don't work on the forums I just know my way around the API somewhat, so I spend some of my down time helping other modders.