Well...Bisley is the lowest, standard NewVaq is tallest, standard Blackhawk slightly shorter, SBH/Montado is a bit under half of the difference between Bisley and NewVaq. In other words the SBH/Montado types are a hair below the halfway point - so they're a bit closer to Bisley than they are the taller types.
Oh...I know what you're talking about. OK...if you take an original pre-WW2 Colt SAA *or* a USFA close clone of same like the Rodeo, the hammer reach will be shorter than a stock New Vaquero. The NewVaq with a standard hammer will have a "thumb reach" distance closer to the post-WW2 Colts (2nd gen and forward). If you put an SBH hammer on a NewVaq or buy a Montado, you'll get a "hammer reach" that's both shorter and closer to a period-correct 19th century Colt.
Which is great if you're a "strong side thumber" - in other words you've either never adopted or you've abandoned the off-hand-cocking method of two-handed shooting that has become a plague in SASS circles. For the longest time SASS banned the SBH hammer, so most of the guns were oversize for strong-side-thumbing - esp. the Old Vaquero that dominated the sport. Hence off-hand-cocking took off - but it leaves you hosed if you have to shoot one-handed.
If you're shooting major loads (high-end 357 or maxed-out 45LC, 44Spl, etc.) you gain no speed from off-hand-cocking. It IS faster if you're shooting mouse phart loads with more or less no recoil...but add recoil to the equation and off-hand-cocking offers no benefit. In fact, crank the power up high enough and it can fail - putting your off-hand thumb across the back of the strong-side hand at the end of the cocking stroke isn't a very good recoil control method.