Gday Duncan - I am the worst possible person tomake reccomendations (just bought a 10" ACF and a top end 4" TV refractor - both suggested below). I would however suggest you also consider one of the better 6" f6'ish Mak Newts around. I just got hold of asecond hand Intes MN61 however I notice Orion have one available and believe it or not skywatcher have one coming out (on thier web page). Looking at the O'seas results with the Orion they seem to stand up and I am not suggestiing they are the quality of Intes (maybe they are but I just dont know) you could have a look at Eddie Trimachis web page and his comments re the Intes.
http://astroshed.com/
Yeah there are some collimation considerations but once you learn the procedure it is fine.
Anyway - just another one to consider.
MB