I open the lid usually only twice in the cook process, the first time to wrap the meat in foil, the second time to take the meat off. Usually we're cooking larger quantities of meat than you'd cook in an average cook or a KCBS cookoff and honestly we cant afford to suffer more heat loss (last cook was 9 18lb whole shoulders, 2 9lb butts, and then 13 or 14 racks of baby backs, all at one time). The thermapen helps check each piece to make certain they're done properly and stored properly. However, I use 2 (not just 1) mavericks et73's during the whole cook; one on front left, the other on back right. It allows me to see exactly how far along we are in the cook and exactly the surface temps so that I can address temperature variances quickly (our alarms are set tight).
Two completely different uses. Both great. I wouldn't think of it as one vs. another.