For the start I will run a few packs through it on 6S and just make sure everything is fine and then up the ante on 8S. I have quite a few 4S packs here waiting to be used. LOL. Anyway I am not even the slightest worried about the ESC. What ever happens to it happens. I am using it within it's specified parameters and anything that might happen to it should be covered by the warranty. I am more worried about the motor. 1717 don't grow on trees. If I blow it on 8S I think I will just cry but I am hoping that Castle was being a little bit conservative on the RPM limit. If the worst happens and I do toast the 1717 I still have a 1520 sitting on the shelf.