The durability is not in question we have had nothing but good luck with the engines. We have not had a engine failure due to manufacture issues. Daniele hand assembles the engines so you know that you are getting a engine that was hand fitted as well as modified. I think that the performance of the engines speak for themselves though. In the US we TQ'd both 1/10 and 1/8 scale at the Biggie as well as won the 1/8 class. We placed 2nd in the Capitol classic as well. One the Florida state series and the list goes on. In Europe The engine led a lap ahead of the entire a final until 2 turns before the finish Daniele's battery went south and was unable to maintain the 1 lap lead. So I would say that the engines have done well. If you have any questions please feel free to PM and we will help you out the best we can.