Howzit Choppie,
There are a few differences between the A1 and the UH-1H, for example the A1 has dual hydraulics, single generator, 212 drivetrain and transmission etc.
I fly both the A1 and the UH-1H in Africa doing sling work and they perform well with -13's. The A1, due to the transmission will lift 10500lbs at sea level and the UH-1H will lift 9500lbs. Performance does drop quite a bit at high density altitudes, but we carry full fuel and a load of 2000lbs ish at 5000ft and 30 degrees.