I'm with Erick - over the years I've switched from "Weaver" and "Iso" to kind of a modified stance that's a bit more natural for certain types of shooting. If you're target shooting, then sure - go with one of the old tried-and-trues.
If you're practicing for offensive or defensive shooting, then you need to change things up.
Thinking that you're going to have time to line up a perfect Iso stance or a perfect Weaver stance during a high-stress moment may be asking a bit much of yourself, not to mention sacrificing a bit more than you want.
Just like we teach QK-style techniques with a carbine: legs slightly bent, toes in the direction of movement, weak leg a little forward, torso slightly forward from the waist, elbows in, weapon at the "ready", looking just barely over your sights.
Weaver vs. Iso pics: