You already know how much you need pneumatic tools in your operation, whether it be on a jobsite or in a home shop, the day of pounding things together with a hammer and nail are done. Not only is it slow but it requires a surprising amount of physical energy and has the added downside that it moves the pieces around.
There are few things more frustrating that getting everything right where you want it and having the fastening operation change the relative position of those pieces. One bad operation and the whole project can be destroyed. When using a power nailer, you can position the piece and with a little care, it will stay right where you put it.
That is all stuff that you already know, but if you only have one air nail gun, you are missing another advantage of using a cordless nailer, the fact that you can use smaller fasteners when the job calls for it. If you are using relatively small pieces of wood, a sixteen gage nail just plain be too big for the operation. This is especially true when you get closer to the edges of the piece. A cordless 18 gage brad nail gun that shoots an smaller nail can make your life a lot easier when it comes to this.
When I was first starting out as a professional carpenter, we only had sixteen gage finish nailers. You would just switch out the length of nail depending on the task at hand. While that was a huge step up from the days when I helped my dad and we drilled and nailed everything by hand, there was one problem I still faced. When nailing the trim around doors or windows, it was not uncommon for the wood to split right at the inside of the miter. When I was nailing by hand, that’s because the head on the nail would split the wood when it was set, and with the air nailer the diameter of the fastener was just too big for the situation.
Once I purchased a brad nailer, this problem went away.
There came a time when I added an even smaller pin nailer to my arsenal. But that is a truly specialize tool. Vital for situations where it was useful, but pretty useless for anything else.