You can use a meade 6.3 reducer on a f4.5 Newt and get pin point stars across a aps size sensor the only down side is a hot spot in the center of the image. I did this a couple of years ago with my 18 " with good results but sold the reducer and bought a w.o. .8 reducer which is useless on the Newt. but brilliant on my ed80. Last week I was having the same thoughts as yourself and came to the conclusion that the Keller type of reducer was the best but out of my price range at the moment so I ordered a Antares 6.3 reducer from OPT on Monday, it maybe a bit more flexible in its positioning than the meade. I am also fitting a larger secondary mirror in the scope plus the use of flat field shots in the image processing should give super fast f2.8 images with no coma.
clear skies Ken.