I've had one of these things in bridge position for a couple of weeks now. Here's my thoughts so far.
It replaced an Airzone, a VERY hard act to follow. Frankly, I was very happy with it, and surprised I removed it. However, I kept reading posts gushing about how the AT-1 had this extra little thing, this "swirl of harmonics" around each note. The specs on the Dimarzio site are pretty similar for both pickups, so I decided to give it a try.
Please note that I don't play anything much heavier than AC/DC, Gary Moore, stuff like that. I'm primarily interested in clean sound. I play quite a bit of country music. I was a little concerned when I hit that first chord with the AT-1, and realised that one man's "swirl of harmonics" may be another man's "dirt". It was only when I turned the amp up and gigged that I became relieved. No, not dirt, it's character! The Airzone is like the guy everybody likes. Solid, dependable. The At-1 has attitude, you either like it or you don't. I like it a lot. Its more cutting than the Airzone, but in no way brittle. Not QUITE as much bottom end, but still plenty.
As I said, I need some country twang, and let me say, the AT-1 doesn't split anywhere near as well as the Airzone. From what I've read, NOTHING does, the Airzone is superb in that area. When I tried splitting the AT-1, I was very disappointed, I'd been spoiled. In desperation, I tried it in parallel, and bingo! I've never been a big fan of parallel wiring, but it just works with this thing. There have been moments onstage where I've been wailing away, thinking I'm in series mode, and suddenly realised I'm in parallel, there's nothing thin or artificial about it. You can get satisfying country twang out of it, unless you're a died-in-the wool Tele fanatic.
So, at the moment, although the Airzone is not yet for sale, I can say that I'm very satisfied with the AT-1. It covers a lot of ground, and does it with style, and some attitude. Highly recommended.