Big Mike,
Below about 6,500 feet you are correct but above that the 47G3B series (with Lycoming 435 and turbo) is far better. At 10,000 the 47G3B-1 and 2 had better performance than the 206A and equal to the 206B. The 47G-4 (Lycoming 540 same as the 12E) was the equivilant of the 12E except it had a quaint thing called hydrualics. Didn't you just love "poping the collective in the Hiller 12 to get the collective to stay in one place?
Both grand old helicopters that did a lot of work in the worst conditions.