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Hi Matt,
I've had a Celestron Nexstar 11 for 3 years and have more recently bought an 11" CPC. I've also had initial misgivings about the optics in each case (I suppose it's natural when you spend a lot of money on a new telescope) - even tried an alternative tube assembly the 1st time. Compared with my 4" refractor, star images were not so crisp and at first I though the in and out of focus diffraction patterns seemed to suggest some form of spherical aberration.
What I've come to realize after lots of time with these optical tubes is that they are pretty consistent in quality. Star images and planetary performance aren't as crisp as in a premium refractor but they're ok and they compensate with much more aperture. Also, proper cool down is very important - vast difference in the star test when the optics are at ambient temperature and this can take hours unless you have some form of active cooling (I've just ordered the Lymax SCT cooler). Also need very steady atmospheric conditions for a sizable aperture to perform at its peak. Just some thoughts that might encourage you not to be too quick to judge yours if you're unhappy.
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