Jeff raves about your 845s. I can imagine that the Hornings love the extra power. It's almost similar to cars. No car likes being pushed by a 2 liter engine :)
After speaking with Brent Jessie I came to the same conclusion about the tubes for my Tron. I was deciding between the top Amperex and the Mazda silver plates. He finds the Mazdas more neutral than the Amperex with great punch and top end sparkle. Unfortunately your triple micas weren't available but he assured me that the 2 mica version with tube dampers would be just as good.
I'll have to try fuses next. It's interesting that you found the fuse in the TW motor controller had the biggest impact.