I have the 15ga. I'm still in the 30 day period and I don't think I'm going to keep it.
I got used to the weight and balance quickly, not a problem. I got it zeroed in so I can put a nail just where I want it. No problems for me so far with the size of the head. I love it in routing use, when all is going well.
I have two problems. First is misfires. I'm using Senco nails, 2.5" and 1.75". When it's great it's great. But it looses it's mind periodically and will misfire 3, 4, 5 and up to 10 times before it will shoot a nail. I change out the strip, re-cock the spring, remove the magazine. It's a big problem. Second is the hammer. It will stick and not retract. This can be caused by a weak battery according to the troubleshooting guide. It happens to me with a newly charged battery. When it happens I have to remove the battery, set the firing option to off and wait a minute or two. Put the battery back on, set to cyclic or bump and it will retract. This has happened several times. Enough times that I know the routine.
The thing is, if I take it back I'll never have a cordless nail gun. I justified it for a specific job and if I take it back I won't be able to force myself to fork over the $400 again.
For $400 it has to be perfect. It ain't.