Mark,
I use David for all my repair work and value his judgement greatly. If you were to talk to him, your fears would be somewhat assuaged. While parts availability is getting somewhat limited, many lenses get repaired and have CLA's without needing parts. The most critical part, the mainspring, if I'm not mistaken (and I could be) has an alternate source availabe or an alternative spring can be used, I forget which.
If a C lens fits into Katies budget best, there's no reason to be afraid of them. Most lenses that need a CLA don't need parts. While I applaud you for bringing it to light, on some forums it's gotten so crazy that people will outright tell someone not to buy one as opposed to buying a clean, well performing one and being aware. Just like the extension tube and jamming myth, blown far out of proportion to the reality. As to the original question regarding sharpness, the majority of C lenses are no different, optically than T* lenses, sharpness will be the same with both, assuming properly shaded lenses.
The only thing I suggest to people is to try one first, as some people don't light the stiffness of the C and T* focusing helicoids and their shape, in that case a CF lens would be easier to focus.
My personal perspective, having had a full complement of CF lenses until recently, I prefer the tonality and rendering of the earlier C and CF lenses myself, the later versions to my eye get a little to sterile looking, a little too contrasty and while the numbers are better, I prefer to evaluate lenses using images instead of test charts.
since we're pointing to other threads/sites, read and take from these what you will:
Why do people concerned from old C T* lenses? - Photo.net Medium Format Forum
http://photo.net/medium-format-photography-forum/00X3cy?start=10
http://photo.net/medium-format-photography-forum/00WnTV
http://photo.net/medium-format-photography-forum/00Wf1J