Hi Mike not knocking Classical Cassegrains as they have there place as do other designs but when i was doing my reseach for my scope I hade a good conversation with Rob Royce about doing a 12.5"Classical Cassegrain of f24 for planetary work as I liked the design location of the eyepiece and shorter OTA from my SCT days but wanted better quality than the commercial SCTscopes.(sorry guys)
Rob said he would do it but insisted that a Newtonian was a better way to go.
Even at f24 and a primary of f5ish the central obstruction was still in the order of 24% and the cost goes up a fair bit for that extra little mirror out frount.A more involved process than a flat diagonal.
The OTA is also more involved with good baffling required .
A planetary optimised Newtonian of f6 or more will have a central obstruction of well under 20% and is easy to contruct.
The man (Royce)could make any scope design that he wants but his own scopes include an 10"f8 and f6 Newtonians + a rather long refractor..
He now offers Cassegrain mirror sets as a standard item for those that must have such a design but from all his writings on his web pageses it is obvious to see he favours the Newtonian.
The best bang for your buck and versatile design.
I am very happy with my RR Newt conical mirror and even though the scope is optimised for planetary work with carefull designing it also works just as well for deep sky.
A CCass is really best suited to planetary use unless you go the expensive Ritchey-Chretien short F ratio then that is more orientated towards deep sky imaging.
I have just learnt to live with the 2m OTA asssembly of the 12.5"and have had to make a mount for it.
If you go to the Rob Royce web site you will see a 10"f6 double truss Newt on an EQ6 with all the instructions to make the scope.
This is about the practical limit for an OTA on the EQ6.
http://www.rfroyce.com/10f6tel/
If your worried about the eyepiece hight of say this 10" scope remove the EQ6 legs and make a low hight pier.
There is room for the scope to be mounted lower as you can see from the pics on his web page.
Your scope is an 8"f6 from your signiture so ep hight should not be a problem if you make a low pier for the EQ6.
Hope this help
Mark