If you're willing to put a little extra work into it, using screws instead of nails can really help make this kind of "light" framing much more durable. It's a little/lot more time consuming, depending on how much you love your power drill, but well worth the extra time, in my opinion.
Are the top and bottom plates already installed? Could you use a 2x2s for the top and bottom plates? Then you could nail (or screw) through from the outside of the plate into the stud.
I have to say that I am no fan of cordless framer nailers. I have had two different ones, a Porter Cable and a Pasload. Both were gas fired. The PC was a disaster. Had lots of problems with the propane cells seating properly and nails jamming. Got the Pasload, worked OK, but slow and the smell was so bad that I only used it outdoors. The gas cells are expensive also. After two days on a job, I went back to my trusty Bostich 88 and ran the compressor off a gen set. The other thing I hated was that it could not shoot 10d wire collated nails that I use in my other air framers. Those plastic bits flying at your face sting and you have to reload much more often. Absolutely hate plastic collated nails!
To be honest, I have not tried one of the new battery operated models yet. For framing, I like the largest, thickest nail.(3 1/4") and most cordless ones don't shoot the same larger nails I use in my Bostich.
Since your projects are at home and you already have a 135# compressor, I really think you will get a lot more nailer for the $$$ if you stick with a Bostich 88 mag or similar. You will be able to shoot 4d to 10d nails. The unit itself is much lighter, cheaper and very dependable.
For what you pay for a good cordless, you could own a good framer, 16ga finish and 18ga brad gun, thus having the right tool for every nailing job.
I have to say however, a good cordless finish gun is wicked handy and the battery models have plenty of power, but this humble carpenter is not sold on cordless framers.
Best Answer
In all the nail sizes specified in the charts, 10D (3") nails are also an option. In the building trade, that is the size pretty much used everywhere when it comes to nailing up framing in anyplace.
In answer to the 8D question, 4 nails will easily fit into the bottom of a 2X4, yes they will cross each other, but only in the plate where the split resistance will be optimal. The angle used to drive them in and the height the nails enter the stud to get a good grip into the plate, should not allow them to collide in the stud.
If the 3" nails are an issue, 3 1/4" nails are available too. I have never seen 16D nails on a shelf in any supply house either.