David - You asked "Do you think that you could train someone as a fine karate-ka teaching only Sanchin, Hojo Undo (Uechi style), kotekitae, two person sets, and general strength work?"
I would say yes (but with some reservations of my own), provided that those two person sets allowed enough spontenaiety to teach the practioner to react without always following the same preset pattern. If everything that we train is based on a set pattern, we will find ourselves unable to deal anytime that pattern is broken.
In the end, as long as you have a holistic system (which is in essence, what you have devised), and use/practice all elements of it, you will be fine. I'm not suggesting that it's nessessary to practice multiple kata, so much as that it's nessessary to practice something besides kata. No part of the system works alone.
Van Sensei - I believe the Chen style of Tai Chi incorporates some very explosive movements into it's forms. I saw a tape of Adam Hsu, a Chen practioner based in San Francisco, and when he moved, he appeared to move with a lot of power and speed. Just a note/thought...
Roy - I wasn't suggesting that kata are meant to replicate a stressful situation, but rather, that they are meant to help us cope with stressful situations. My attempts at inducing stress in myself at the beginning of a kata were simply a way to try and make the neuro-muscular connection between these movements and a high stress situation a little stronger. (Note: I have no idea how effective this is...it's an experiment, after all).