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What size aperture would you consider?
And it depends whether you would make the optics or purchase them?
You should consider the possibly the TCT design could cause distortion at the focal plane because of its off-axis nature. But I haven't verified this in the design you mentioned. I would think the TCT would give a very large focal ratio, making the telescope suitable for mainly planetary viewing. The optics would be easier to make than say an off-axis paraboloid, but if you are buying the optics, the off-axis paraboloid may be a better option.
If you want up to a moderate aperture of 8 or 9", you could consider an off-axis design, such as offered by DGM optics, who make paraboloids by cutting the outer section of a larger mirror, as Janoskiss mentioned. This should give excellent results, rivalling the best refractors...no central obstruction, no chromatic aberation, no off-axis alignment aberations, but you would still have to deal with tube currents, compared to a refractor. I'd say the off-axis paraboloid would be easier to build too, and no spider to worry about, and no need for low profile focusers either!
I think the cost of the optics from DGM is not cheap, though not prohibitive, but then a hell of a lot cheaper than Fluorite Apo's. From memory, the DGM Optics have had excellent reviews. By the way, I don't own one, just a humble newtonian.
Cheers.
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