Just found this site - looks good.
I'm jealous. I am still using a 5hp machine I rehabbed as a basket case years ago. Drive is 3 car wide x 100 ft long fronting on a major 2-lane US highway (US195 in Eastern Wa). Needless to say that even a 2" snowfall will build quite a plow berm across it. I have to "nibble" at it in the lowest gear. Same when I have to double (sometimes triple) blow. That poor machine has handled banks over 4ft deep but it does take awhile.
Re: throw distance - a governor will maintain whatever speed is set by the throttle, be it WOT or idled down. Engine speed does not not change due to load as long as it isn't heavy enough to overload the engine. Snow will blow further if the auger is kept well loaded. Why, I don't know but it is easy to demonstrate. Take say a 4" snow and hit it at whatever speed the machine will take. Now drop gears down about half and compare the distance. To me it is totally couter intuitive but that's the way it works.
Harry K