Harry,
Yes, my engines all blow a little bit of black smoke on a quick no load throttle up....BUT, they respond quickly and positively when a load comes on the governor. At idle, slap the PTO switch and the engines just bark once as the PTO implement spins up....no stumbling. Hit the snow pile with the thrower running at WOT and the engine just barks a little and eats the snow...no need to gradually come into it.
I will admit to having nice tight carbs on my stuff, either little wear, or bushing kits...they are necessary for good tuning and crisp throttle response.
Wayne,
When plowing with a 12hp gear drive and 19T second, you can out run guys with the 16T or 17T second and still not need to be all the way down in grandma 1st. Backing out of the throttle a little fixes that, but like you, I would never do it if it was lugging hard throttled back in 2nd(you are correct, in that case that is exactly why you have gears). On the hydros, if you are pulling it even moderately hard WOT should be used IMHO.
Oil:
Mine get Valvoline 30W in the summer and Motorcraft synthetic blend 10W-30 in the winter. Like many others, I think the new oils have solved our need for "Low Ash" oil.
In air colled engines just remember to "change early, change often" and run a little MMO in the gas....then all should be well