Donnie,
Your experience with comparing drivers with the DL1 is essentially exactly the same as what Miles Beam and I experienced when we codrove his Vette in 2005 and compared GEEZ runs after the events. We then had ideas for driver improvement for the next event.
Ditto for what I expect I could realistically do between runs and that is with just one driver. Other than a quick check of revs on my recording tach to help with borderline gear shifting situations, I do as you do.
That said, I wonder if the MQGPS display would allow a quick identification of relatively low g's in a particular corner where I "whimped out" but wasn't sure it was necessary to do so? If so, for me that might be the biggest potential value at a major event.
I'm looking for an excuse to spend some of my tight budget on a MQGPS but so far it looks like more seat time and/or more sets of new tires would be a better investment . . .

Dick, if you are going to be in Greenville, I would love for you to try out my MaxQ.
I love helping people spend money.