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My opinion is for imaging an 8 inch Newt with high grade optics and a carbon fibre tube like you are looking at would be far more capable than a 92mm APO. To my eye Newt images are very pleasing and very tight stars. I would be concerned 92mm may be just a tad not enough aperture. I had a nice 80mm APO once but it really didn't have enough aperture. Would 92mm have enough? I don't know - have you seen a lot of images from one?
The downside to Newts are collimation, tube currents, coma, and flexures.
Collimation is a matter of having the right collimation gear.
You really want a fan. Carbon fibre is good as no expansion and light.
No expansion means the same focus spot night after night or at least very close
and it does not go off during the night.
Coma is a matter of having the right corrector.
Flexure - Newt seem a bit more likely to suffer from flexure as the focuser sticks out the side. I see a lot have the camera hanging down under the Newt no doubt to ease that sideways pressure.
But then when deciding on gear, I think you should work backwards from the type of image you most want to take and then work out what gear you would need to achieve that shot.
I used to have an 8 inch Vixen F4 newt as have a lot on this site. It was hard to collimate until I got a cheap Antares laser collimator and then it took 5 minutes!
There is also the 8 inch Boren Simon F2.8 imaging newt. I think they sell for around US$2500 or so. F2.8 may be a little touchy for collimation and flexure but it would also be amazingly fast.
Orion Optics UK make really good optics. Look at John's recent images with one.
Greg.
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