I recently converted my guns over the cordless, and have been very happy so far, though would have been nice to do it all on a single battery platform. 15 gauge Milwaukee, 16 and 18 gauge Dewalts, the 23 gauge Makita pinner. If you're looking into the Makita, bear in mind that they just recently released a second generation -- I learned this a couple of days after I bought the first gen., so I had enough time to return for the newer model. The newer model has less of an issue sinking the longest pins into hardwood, whereas the older one struggled.
Going cordless has made a huge difference, even when I'm just working around the shop, since I don't keep my pancake compressor loaded with air when not in use. I can just grab a gun for a few quick hits while jig making or something that only requires a couple of nails, without having to wait (or suffer the ear abuse) while the compressor fills.