It's very simple folks, if you don't get a visa you will be risking deportation and all the hassle that would cause jobs etc.....
I am going accross in March for my CPL etc and I will be getting a Visa, because for $130 and a day in London it's not worth pissing off the USA.
You cannot argue with a goverment you will always lose, they are bigger than us and we are in their country, painful as it may be we have to do what they say, if we want to be there.
I used to sell luxury cars for a living, (3 pointed star badge) when we used to do Cherished Transfers the rules seemed to change all the time, no point disagreeing as the staff at the wonderful DVLA and VRO's, they can do what they want, just do what they ask.
The same goes for the Americans and any other goverment, we are guests in their counry and if they want us to fart around getting visa's and fingerprints, well so be it. Thats the price you pay for training there.
FF