I may have found the source of my data drop problems. I hope this helps others.
My wife and I got Droid Bionics two months ago. It was great, but after a while, we both experience periodic data drops that would last a few minutes to up to an hour. Finally fed up, we invoked the Costco 90 day return policy and exchanged them for Razrs. Initially, the Razrs were data-drop free, but after a week, I started to see data drops on mine. However, my wife's Razr continued to work fine. This led me to look more closely at how our phones are set up. I had been using LauncherPro on my Razr, while my wife was still using default Home. Previously on Bionic, I changed both of our phones to use LauncherPro.
While having no data, I used Home Switcher and switched back to default Home, and data came back within a few seconds. Since then, while on default Home, I have not seen my data drop. For whatever reason, I think LauncherPro has been causing my Razr (and perhaps Bionic) to drop data periodically. I don't know if other home replacements have similar problems, or if there are other causes of the widely observed data drop problem with 4G Droids. But if you are experiencing data drops, and you are using a home replacement, it is definitely worth trying to switch back to default Home to see if there's an improvement.