Donkey497, i agree, it is a pain having to repeat security,however, i guess i do it so often that i have found the quickest routes in the airports i use. There has been a marked improvement in the attitude of immigration and customs officers in the last year, some are even quite friendly and chat whilst processing you, the officer at JFK did this just last week, but i am sure there are plenty left that have the old attitudes still.
In my opinion the original poster should save the money and not worry about the US transit, good luck and let us know what you decide.