Tire sizes, tire presure (both front *and* rear), launch rpm (not to mention actual staging technique, re: bumping in and then getting on the coverter vs getting on the converter and then bumping the car in), taking extra bumps after staged, staging alignment, sunglasses, choosing a lane based on the sun's orientation with the tree, shock settings...
Changing a converter just to move r/t sounds like way too much work for me, George!
But otherwise great post! You hit on the most important thing -- if the driver's not consistent, you can throw everything else away, because you don't know what you're adjusting FROM. Race or test a lot, and worry about becoming a consistent reacting driver first. I don't care if you're .080 green or -.020 red all day long, just as long as you are *something* all day. Once you've found *your* spot, then you can go to work on the car.
Some people think that there is just one spot for a driver... that may be true for some, but if you mess around with a practice tree long enough on different rollouts, you may find that you can be comfortable in several different sweet spots that may be several hundredths apart. You may have one "best" spot, but there may be others that are quite good for you as well, and give you a fighting change. I've driven more than one car that I had to leave on the 2nd bulb going out... cars anywhere from high 15's to high 9's!
Another important note is that all of these opinions are just that -- listen to everyone, then go figure out what works best for YOU. Every driver is different. Chip Johnson is a killer top-bulb racer, but he's a tree counter when bottom-bulbing. Some people like to block, and some are worthless if they can't see it coming (me). Arm yourself with information and seat time.
I guess the best advice I can give class racers is what I told Jim Bailey earlier this year: "Approach driving like you do building your car. Break it down into its component pieces and say 'How do I make that piece better?'"
I've been working on a Guide to Bracket Racing off and on since college. I'd finish it someday, but I keep learning stuff.