G*3 is about 20.00 bucks less. Most think the g*3 looks better then g*4. I own both and the g*3 do look better to me. A glock is a glock. Can't go wrong. Go for the .40,And pick up the 9mm barrel for it.So then you can fire both.But if you get the 9mm-.40 Will not work. As to be the .40 to .9.. And 40's and 9mm same price for the pistol.

And if your using it for ccw the g27 is the right size. Mag 9+1.

Depends on the person. I wouldn't pay more for a gen 4 because I wouldn't buy a gen 4. My gen 3 fits my hand fine so the different backstrap is useless, I can reach the mag release just fine so the newly designed one is useless, the texture on mine is fine with me so the newly designed texture is useless, and there isn't a chance that the recoil spring in my gun is the one that causes malfunctions. For me, they tried to fix something that wasn't broke. People say the recoil spring issue has been resolved and the new features appeal to more people. Good for them, I don't care, for me the gen 3 is perfect.

I understand the "if I don't need it, why buy it" thinking, but 5 or 10 years down the road, the G4 will be the "modern" weapon and the "G3" will be the older one.

A good comparison is to look at the selling prices for a G2 vs G3. That will give you an idea of the value. If the G2 is more than $40.00 cheaper then it makes sense to buy the newer weapon.