I much prefer 4V to 3V. The toughness of 3V is overkill. Kinda like shooting squirrels with a .375 Mag.. Yeah it'll do the job but isn't needed. 4V is plenty tough enough especially in smaller to medium sized knives. Oh, and keep this in mind, I grind my knives THIN and run them HARD.
I've driven a 10V/A-11 blade .080" thick and ground to .010" thick behind the edge through seasoned, cross grain, Osage Orange/Bois d' Arc & Axis stag antler with no damage. Just a small shiny spot after the antler. That's tough enough for any job a small to medium knife will need to so. I'm telling you guys, toughness is WAY over-rated in knives.
Edited to add that the 10V blade was at 63 RC.