You can often pick up a meade 10" ACF scope for a lot less than a C11, and the Meade 10 ACF I had was considerably better than a C11 I had a loan of.
With SCTs it seems that even within a particular model there has been a lot of quality variation over the years.
To be blunt, if you want to do planetary, get a star test done on the scope you want to buy, there are some dogs out there and you need the scope to be as perfect as possible to eke out the best performance for planetary.
Also, how is your seeing? If you seeing is usually poor, you can actually get better performance from a smaller SCT than from a large one.
I've seen a C9.25 outperform a C14 for planetary on less than spectacular viewing nights (but on the one or two brilliant nights a year I get here, a C14 smokes it!)
Take a look around at planetary photos taken on a C8 and a webacam!
http://www.flickr.com/photos/zamb0ni/6085522975/
or with an imaging source camera.
http://www.flickr.com/photos/jasmel9...in/photostream
A C11 can be a great planetary scope, but a 9.25 or even a C8 can give amazing results too, and depending on your seeing, may be all you ever need.