I just installed one with a Furuno FCV 620 last summer. Granted, this is my first non-transom mount ducer but I love it. If you are worrying about the quality, don't. I think it's an awesome transducer. Plus a real easy install.
When considering the 600W version it has the exact same guts as the in-hull P79, transom mount P66 and more traditional style thru-hull B744. So mounting configuration is the only consideration. The thru-hull ducers work best at higher speeds as they have the best contact with the water, no other advantage in performance besides that. Here is something I wrote about ducers:
Thanks to all who replied!! This was the kind of feedback i was looking for. Any feedback about the 1kw, i was told that airmar's 1kw is at the lowest end of quality. I am looking for a step up in performance from the P66. Thanks again everyone.