I flew from LHR to JFK last month and personally was quite surprised how lax they were with very basic checks.
I work at BOH and am personally quite proud of our security. The team do a really good job and I recently noticed them checking all thick soled boots.
I was wearing such a pair to JFK (I think part of me wanted to test them!!!) and I was not even asked to show them! We had some random checks at the boarding gate but to be honest the security going to the statue of liberty was MUCH stricter than any airport I have ever flown through! (The even x-rayed our watches and my brothers Polo's!!!! Hello, you can see through them!!!) Oh well.... C'est La Vie!