My experience is the reverse of yours. The governor responds more quickly to the need to open the throttle when there is more tension on the spring. The governor will maintain engine rpm at the set level as the load increases by opening the throttle to full throttle. If the load continues to increase then the engine will slow since it cannot develop the necessary power to continue at the gear speed selected.That's governor droop which is normal.
The outermost hole will let the engine droop more before it opens the carb all the way although your no load high RPM is higher...the reason it increases your RPM as the hole isn't in perfect relation with the angle and due to reduced leverage on the spring it simulates a stiffer spring...the first hole for the linkage allows the least amount of droop..an engine is more apt to hunt in that hole..then we have the middle hole for stock..a balance of droop vs the possibility of hunting.
The percentage difference of droop across the holes can be a fair amount.
Governor droop is generally 10 to 15 percent.. with you in the outermost hole it may be a little more.. but let's go with 15 percent..when the engine is fully loaded just to the point of full governor..your engine speed would be 3213 RPM.
As we can see you weren't approaching that number so actually have plenty of power to spare.
I would give it a real good workout..lots of snow and see what the engine pulls down to... If your end of driveway was already deep and tough ... I would say that big engine is fine as it wasn't being pulled to full governor yet.
Remember you have a high speed Impeller which requires alot of power.. so given the same task you will use more power than a typical machine... It looks as if that engine is fine from what I am reading
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For the op's engine speed to drop from 3,780 to 3,400 or so the engine is not powerful enough to maintain the throughput in the gear selected for 8" of light snow compared to more than 8" of heavy EOD snow. That is normal. So further experience with the machine will allow matching of gear selection to snow loading.