I have Bostictch pin nailer and it does everything I ask of it-would buy again in a heartbeat.
When I worked for a living, when trimming windows, we accurately measure and assemble trim on a flat job site bench. This was well before the time of pin nailers, but after biscuits were becoming common. We would install the smallest biscuit at the miter, and then nail with a 16 ga. gun, from the top to hold. May seem a bit slow to some, but don't forget the story of the tortoise and the hare-after setting up the method, two of us moved dayam quickly.
If the thunder don't get you, the lightning will.