It looks very interesting! I wonder how the pres hold up to the Sound Devices?
As Rick R wrote they should be the same as the ones in the F8
You can find that video here:
https://www.youtube.com/watch?v=PM6VOEYpm4g
Here are higher quality samples of the comparison recordings:
Sound Devices 688: https://soundcloud.com/bhproaudio/sounddevices-688
Zoom F8: https://soundcloud.com/bhproaudio/zoomf8
Some have commented that they do hear a noticeable difference between the 688 and F8, but only you can decide whether that difference is worth the extra money in your particular case.
Curtis Judd has quite a few videos on the F8 and he now also owns a Sound Devices 633
You may find the following videos helpful:
Zoom F8 review Wrapup: https://www.youtube.com/watch?v=FSVsZFVPhxY
Zoom F8 Input Limiters (As mentioned by Rick R): https://www.youtube.com/watch?v=KYe-0cO2M8w
Sound Devices 633: Why Do Pros Use Gear Like This?: https://www.youtube.com/watch?v=hDEp34fkbQ4
He's got many interesting videos in his channel, also a few more on the F8.
Good luck on chosing your gear!