Nick
I'm at work and my Lama manual is at home. I will jpg the IGE and OGE charts to you tonight. But if the aircraft can handle a 1.500 pound load in those conditions it stands to reason that it has more than adequate power without the load. The seismic and core drills that I moved were broken down into 1,200-1,500 loads. The Lama moved them day in and day out.
But before we get too far into Lama peformance I have had the same phenomonen in the UH-1H with the 1,800 hp engine, the Hughes 500D, and the Jet Ranger series. It is not machine specific. Ask any logging pilot and they will tell you that they make their money at the edge of settling.