I can show ya a pr of holes in my left leg where I shot myself with a 16, 100 psi and through both bones out the back, took 3 guys sitting on my leg to hold it still as I punctured the achilles tendon.
it was not fun at all, have shot myself 4 times total in 30 yrs of carpentry, left leg was tied back safety, others were wood splitting or ricochets.

this, all I have bought for the 30 yrs I built, works great and nails are the cheapest you can buy but still the same quality as duo fast etc.

lowes carries them.

as to the psi, most all say 90psi, I run at 100 and adjust the nose for depth. there is an allen screw on the front (you can see it in the pic sticking up) and you loosen that and slide the safety down for less depth.

Why don't you rent one?

If you buy, buy paslode

I know alot of people nail planks to the runners, all of the fences that I have built, I use treated screws and screwed them in. Less likely to back out or get loose. I use a cordless drill. Might be something to consider and then you don't have a $300 tool that you will never use again.

i like paslode , have about 5 guns but ive phased them out and using hitachi now, plus i cant find anyone to work on them anymore, theyre complaining they cant get parts.

I've done quite a few board on board fences, and have gotten to where I'll nail the first layer of pickets, and screw the outside ones. I've got a Porter Cable nail gun that's nailed thousands of times, still going.

If you're local to Mckinney, come get it. Bring a case of Coors Light back with you when you're done with it.

I repair and replace fences. I have a Hitachi coil siding nailer which I use for my picket fence. I also nail at an angle instead of the regular 90 degrees. This seems to hold the picket fence better in the long run. Just make sure you use ring shank nails. If you are just going to use it once then try renting it at Lowes or Home Depot. If you do not have a compressor, you can rent that as well.