Just found a site that did noise floor tests with a whole bunch of popular field recorders.
The Sony PCM-D1 sounds AMAZING, but it's $2K. The Sony PCM-D50 sounds second best, but the hardware itself is dumb (Memory Sticks only, stupid Sony proprietary media) and it's missing important accessories like a wind sock and a tripod. Sony being Sony, of course, they sell them separately for an arm and a leg, respectively. If it weren't for that, I'd buy it.
The Zoom H4n and the Tascam D-100, the two I'm most interested in, both have annoying noise floors. The Tascam is quieter and is less hissy, but it has a high-pitched beep every second - it's probably the memory being written. The Zoom has a smoother floor, but it's a bit louder and covers a larger frequency range, like white noise.
Hm, that Sony PCM-D50 is looking pretty good right now. It has an amazing battery life and great sound, but accessories are through the roof.
WHAT SHOULD I DO D: