I love this beacon. I haven't had to use it for rescue, thankfully, but have used it when out and about. First of all, it fits great. The slight curvature of the design even adds a bit of comfort and the straps and sheath are comfortable enough to wear. When I used this at an avalanche course where everyone was using the BCS beacons, the instructor was blown away with how fast i was able to find a buried beacon. He was also impressed with the beep feature.
I love it too. As you get a signal it starts beeping somewhat slowly, and speeds up to a pulse until when you're right over your target it goes to a solid tone, very similar sound to a cardiac monitor. Maybe they made it that way on purpose as a reminder to get your butt over and start digging. Anyways, this is very accurate and responsive. There are only three arrows (one center, and l&r) but with the distance reading and the beeping i have had no problems finding other beacons with it. if I were to buy again, I wouldn't hesitate to look at the D3. I really don't have any real complaints about it. Keep your batteries fresh every season.