You've certainly put a lot of time and effort into your solution, Warrior of Toys, and it looks like it will work!
Still, I have to agree with Martin in that I see no reason why anyone would want to combine Steck with System X. These are two distinct building systems, each with their strengths and weaknesses, that are different sizes and look completely different. Combining them would look awful. If Playmobil wants to do something for the adult enthusiast, I would suggest producing Steck again and adding round towers to System X.
Frankly, Playmobil could have avoided all of this frustration and the new awful click together system if they would have simply stayed with Steck all along.