I could have ordered a 30S but they are still only Gen-3's. They way I grip on Glocks I need the beavertail grip on the Gen-4's. The Gen-4 30 is basically the old 30SF with the ability of changeable backstraps. I almost did a 29 to go with my 20 but after shooting one I decided against it. What I really wanted was a 17L but they are no longer produced.
I love my G30S. Yes, it is a gen 3, but you could always order a beaver tail. My G30S with a beaver tail is pictured below. It's the one in the middle.