Why do cars go missing all the time? Because people dont have immobilisers and decent security. Seriously, 9 out of 10 threads posted up here of stolen cars are simply due to the fact that people that didnt have a decent alarm on their car, which could mean that a majority of thieves are joyriders and amateurs - otherwise there would be a lot more high-end cars equipped with decent security stolen!!
I've never heard of a car which has been stolen when there was no steering wheel on the car. Sure, it could possibly happen if a car was parked in a location where a tow truck could access it and it was towed away - in that case only GPS/GSM tracking will help!! Not having a steering wheel on the car means that you instantly rule out 9 out of 10 possible thieves: the amateurs and joyriders - that's pretty damn good for under $100 in my opinion! Sure, thats an estimated statistic but I'm certain that the large majority of thieves arent pro's!
As for taking the air bag wheel off - thats a personal preference. Safety vs security!