Alright. So I can see this being an issue in the near future.
For my build I went with the Micargi Stealth frame. However, the dimensions of the frame do not allow the engine to be mounted with the stock kit. As such, I had to purchase the JNM Super-Mount to allow the engine to be mounted and clear the pedal sprocket. In order to prevent vibrations and motor movement I tightened the engine down, which cracked the mounts. Reading the one review I could find for these things online, that guy had the exact same issue, resulting in the mounts completely cracking and falling off the bike. Followed by the engine falling off in motion.
I want to build and sell my bikes and these mounts are not going to cut it if they continue cracking. I need some suggestions for alternate mounting methods. Preferably some good premade mounts that will reach long enough to get to the tube and be wide enough to comfortably fit the tube. Any suggestions would be greatly appreciated.