Ok, after repeated soakings in beer, I can report further on the AN-LP1. And I also soaked the antenna in beer, too.
My conclusion is that, for indoor use, this anteanna is usually better than a wire. It rejects noise very very well, which is my main complaint when on the road and trying to use a longwire inside a hotel room. However, even with the noise, my EF-SWL beats it hands down when I can get the EF outside, which is not often.
I have been using this with a Sony 7600GR, for which it is designed. There are confusing statements in the antenna documentaion and on the web that the AN is powered by the 7600, and the question is whether a non-Sony antenna will work when plugged into the external antenna jack. The true situation is that the Sony puts a very weak voltage on the antenna jack when it is turned on, and this turns on the AN power supply. Other antennas can also be plugged into this jack, and they work fine. The AN can also be used with a non-Sony radio; in that case you have to manually turn the power supply off and on, which is no big deal.
All in all it's a good antenna. I have been running it on the original batteries for at least 40 hours now, with no signs of failing. The lack of gain makes it problematic for very weak pirates, but it is definitely better than a longwire indoors, and it works well with broadcast and utility stations. I paid something like $120 for it on eBay from the guy in Japan, and I don't regret it.