Victor,
You've got a serious set of requirements in your first post. To be honest, I don't think the 109 would fit all that gear and people...especially with a requirement for 3 hrs endurance. I'd say you'll have to go for the 76 or the 412 if you need to get that kind of payload in the machine...don't know whether those machines will go the distance (3hrs). I have to agree that the 139 is probably the perfrect machine but if helipads aren't workable and lead time is a problem (which it is) then your choices are limited.
The real pitty is that the best machine for the job as you've stated it doesn't sound like an option because its costly...you're the poor fella who's got to convince the people with the purse strings that its the best choice...I don't envy you.
Best of luck...let us know how it all works out.
HP