I just upgraded to the 8"Edge from the normal 8se OTA.
I use the EQ6R pro.
I think a 9.25 will be getting a bit too heavy for a EQ-6r. You have to keep in mind the weight of a rail, a decent guide-scope and guide-rings, as well as a camera.
You might be able to save weight with OAG.
Also the weight of all the accessories like star pointers, finders, dew shield and all that.
Also you will experience vignetting with a full frame AND focal reducer if that bothers you.
Check out these flat frames showing it.
The Vignetting is fine without a reducer, and planetary is not an issue as you use the centre of the camera chip.
Collimation isnt too difficult once you do it a couple times, but it's one extra thing to keep in mind, especially since it's far more critical with planetary. I messed up capturing Mars at opposition last year due to collimation being out on my imaging nights that came before the big dust storm that blurred detail.
I think SCT are great for planatary, I use either a 2x or 3x barlow to get the right sampling with my ASI120MC. Using fire-capture to image and guide works really well for me.