I have run two 16 awg guns off a 2 gal Craftsman...small/light enough to carry around, but it is oil lubed and has a pump on it that puts out nearly 3.0 cfm @90, has a duty cycle of 50%..... I wasn't speed nailing base tho....I was installing built up crown.
Here is a link with 73 reviews...4.xx stars out of 5.
http://www.mysears.com/Craftsman-2-gal-Air-Compressor-with-17-pc-Accessory-Kit-reviews
I would give it 4 of 5...but I have only had it for a month and I got it used for $50, including the gas to go get it, I changed the oil in it to synthentic, so I guess in total it cost me $56.97.
I like its low center of gravty, does not tip, infact I usally have it strapped to the jump seat with the lap belt in the back of my Ranger. Has a decent air filter on it. It is not super loud, but by no means quiet....it operates at 100 psi on -135 psi off (at least mine does, and I am aware it is supposed to only go to 125...I guess I got lucky, maybe I should go in and turn down the cut-out pressure down), it recovers in only around 10 seconds, only pulls 10.5 amps, oil lubed, stainless steel braided lines instead of copper tubing with compression fittings that tend to wear and break...
Of all the compressors I have used, which is not many, 4 gal Husky/Campbell Hausfeld, 4 gal Ridgid, 3 gal Speedair, 8 gallon unknown brand, but old and hell and pulls 19 amps and it is a beast of a compressor, I like my little guy alot...but I keep the larger 4 gallon one around for the larger jobs....
But I have been on a quest to find the smallest tools that still get the job done, lighten the load...