I would agree with Chopperpilot 47's remarks - I know that there are much better schools around the US and I know of others who have had much better experiences (with training and maintenance).
However, the practical point that I would emphasise is that although it may be legal for you to command a G-reg helicopter on a US license, check carefully that the school from which you plan to rent is willing to let you loose without a JAA license. I was told it was due to insurance restrictions but at the end of the day it is their decision.