Ive used the boss,for a season,and the western for a storm,Id buy the Western first,but the Boss is quicker no doubt.I like the Westerns trip,and build better.All my Uncle's Bosses have cracked in under 3 yrs at the pivot pin.
AS far as speed goes the boss has faster hydros, but as regards to which one will clear a lot faster, the answer would be both.
Operator experience will mean alot more for that equation than plow brand.
I personally prefer the western v plow ( I have 2 of them), but would buy a boss if the price was right.
You could give a 6.5' plow to a pro and a 10' to a beginner and the pro would probably get done faster.