3 and 1 is indeed much faster, and you wouldn't have the hassle of switching to your melee before attempting QQ method. Eliminating the fact you might swap to your primary weapon then to your sniper which is much slower and less portable.
The tactical knife switches much faster then the regular knife, and its more portable.
Just a tip, o-o. Because quickswitching is meant to be faster then waiting for the rifle to go through the reload animation you best stick with a knife when quickswitching.
Binding mwheel up and mwheel down would be annoying for my mouse, since its a gaming mouse when i slide the scroll it doesn't stop, its just keeps spinning, heaps useful in css. :L