Tim, you are right that the tourbillon averages the errors in the vertical positions. However a clock, unlike a watch, sits in one vertical position its whole life. So the balance could have a huge poise error and be all over the map if checked in several vertical position but still remain accurate
I don't think any claim was ever made that the whole watch is lubrication free, just the escapement. Some through-the-grapevine talk about the problems Omega encountered when implementing the escapement brought up this interesting tidbit- George is oldschool and cleans his parts in benzine. Benzine
One more bit of information to muddy the waters. Steel not only changes it's elasticity as a result of temperature change. It also changes as a result of the stress on the steel itself. I was informed by an engineer and model maker for Bulova that they experienced big problems when they switched to