I had a real problem with chafing and saddle sores for about 6 months while using Chamois Butt'r. About 18 months ago, I switched to DZ Nuts and haven't had another issue with the undercarriage. On the odd occasion that I get caught in the rain, or covered in filth while on the CX bike, and am lucky enough to get a chafe spot, a little of DZ's product takes care of it within a day or so.
As others have said, it's a bit tingly upon first application, but after continued use, the tingle gets less and less. It will open your eyes wide on a chilly morning though!
I've thought about trying other stuff, but can't bring myself to do it.
And it's not terribly high dollar, especially when you consider it's keeping your chassis in proper working order...