As far as nowadays (FlexRaid 2.0 u11)
- the main snapshot limitation is IMO that "edits are not recoverable",
- and the main concern with the RT mode, on Windows, is that "deletes" are immediate and permanent,
wouldn't this be helpful : to be able to define a Pool with one/several PPU updated in snapshot mode and one PPU updated in RT mode

With that in place:
- I would not be that afraid of loosing a disk while Parity is not updated yet on the PPU/Snapshot (as the PPU/RT could be used to restore that disk* )
- I would not be afraid of deleting files by mistake as I would be able to restore them from the PPU-snapshot
Does it make sense ? Or absolutely not

(*) I presume if a disk crashes precisely
during an edit, using the PPU/RT will also restore corrupted files as this PPU is also updated with a some delay.. But wouldn't be "less damage" in that case than restoring from a PPU/snapshot not up-to-date.