Do these detect and deliver immediate readings as fast as the RPMs change? (On a street driven car thats obeying the law) Or do you have to drive at a certain RPM for a few minutes to get an accurate reading? just curious.

Yes they are real time readings and are very accurate.

Then Santa will bring me one. :)
Anyone know of a inexpensive brand that will do the job? Otherwise, the research begins...

I like AEM

Actually I'm having a problem with noise in data logging 02 because the Innovate LC-1 and Bosch WBO2 is too damn fast. Innovate claims you can get noise because the LC1 is capable of reading individual exhaust pulses. That's pretty damn fast!

So an idiot than can read these meters, can tune a carb with ease. No more guessing and trial and error, huh?