How much skill?

Agreed. The BB is not a HUGE part of it but it can play a siginificant role depending on environmental elements. The "heavier" the BB the less it is effected by wind and brush. But the downside on a heavier BB is a loss of range.

Most people I talk to shoot .28's, .3's, .36's, and .43's.

The stronger the gun usually the heavier the BB.

I think I can agree with the 60:40. It does come into a large effect. But not price just the rifle itself but how the performance of the rifle is. Of course the parts to cause the performance is going to cost you and it seems that way but not always. You basically need a accurate rifle that has some distance with it. Say hitting a human size target at 150ft+ shooting around 525-550fps.

Now it will come down to the skill. Anyone can purchase themselves the best of all rifles with the right amount of money but that doesnt mean they will know how to use it. Not only that but all the other essentials of Fieldcraft, Marksmanship, Tactics. Its the combination of these that make the weapon itself. The man behind the rifle is the weapon. The rifle is just a tool. But it is easier cutting down a tree when you have a chainsaw rather than a hack saw.