I've also heard that a patch is more likely to develop a leak than a plug. As the tire heats/cools and flexes, apparently the patch can loosen, but the plug stays put.
Over the years I've ridden nearly 700,000 miles and changed at least 100 tires. I've plugged dozens of them. The worst problem I ever had was one that developed a slow leak. Those sticky string type plugs work great and develop a nice, patch-like blob inside the tire. They're also inexpensive and easy to carry along.