Mikey D,
Are you sure that the school you are planning to attend in Hawaii is authorized to issue the J-1 visa? To the best of my understanding there are only a few flight schools in the US who are allowed to issue J-1s for flight training, and only two of them (Bristow and Hillsboro) offer helicopter training. Furthermore, the US State Department stopped adding schools to the J-1 authorized list in January of 2006, so there shouldn't be any new schools on the list.
I know of at least two schools which specify on their websites that you cannot have more than a PPL + 50 hours beyond PPL in order to qualify for the J-1, but I can't find any official information about this requirement. The only stipulation about prior experience and eligibility for a 'trainee' category J-1 comes from 22 CFR Part 62.22(j), which states that "...trainees shall be fully qualified to participate successfully in a structured training program at a level appropriate for the individual trainee’s career development. However, such training shall not be duplicative of the trainee’s prior training and experience." Perhaps the schools are using an arbitrary value of PPL+50hrs in order to ensure that you aren't duplicating prior experience when you go there. The best answer would come from the "Responsible Officer" of the J-1 visa program at the school you intend to go to.
I'm currently studying in the US on a J-1 Visa and loving every second of it!
Cheers, SS