I'm also exited about these new recorders! Are there any high quality audio samples available online??
I get a slight hiss with my current recorder and reduce the noise in post. I'd really be interested in hearing for myself how quiet these preamplifiers are. I saw a video where a reviewer did recordings (without a microphone) with the same gain level on a Tascam DR-60DII, a Zoom F4 and Sound Devices 633 and analyzed the noise levels in post. The noise on the 633 was about 11dB lower than the F4. Obviously these three recorders belong to each their class and price point and noise is certainly not the only differentiating parameter, but it's an important one for my use. So far I've only found one video and one podcast where the new MixPres where used for the recoding - and with music in the background of the video and compression added to the podcast, you can't really judge the noise floor at all.