Could do similar to video compression and just store a complete snapshot every so many revisions or if the age of the last edit > a certain number of days to make it more fault tolerant while saving space.
Discussion
sure but i think if you store those different versions in a single key of a key/value store with decent sized blocks every repeated segment is gonna get squashed down anyway
it's only fat on the wire, which isn't really a big problem, especially because it's already pretty squashed by standard websocket compression... flate or whatever it is