Not sure. If you look in the F8 manual at the block diagram on p.184, the M/S circuits, polarity switches, and delay sections (all of which I wish were available upon playback) are all on the input side of the bus, unavailable to the player side. However, that diagram does not explain how M/S can decoded on playback by routing those channels prefader (which unfortunately means no level and M/S ratio control), so maybe there is hope!
Another function I would like them to update via firmware is a modification to the input Trim Link function. Currently when any set of channels are trim-linked, their input gains are automatically adjusted so as to be equal to each other. In other words, all linked channels are forced to have the same input trim level. Took me a while to realize what was going on whenever I'd link them so I could adjust pairs or the entire bunch simultaneously with a single knob-turn, I was eradicating the relative input trim differences I had set between the channels.
In contrast, the similar Tascam DR680 "Channel Ganging" feature does allow for different trims between ganged channels. One can gang/un-gang various channel combinations to adjust pairs in unison or the entire bunch together at any time without automatically resetting the trims and screwing up the relative balances. If one does want all linked channel trims to be identical (say for an ambisonic microphone). They can be set that way before linking them.