I'm working on it, it has changed from earlier Intel series drivers and it is related to how write throughs are handeled.
(just like write through vs write back on caching raid controllers)
The thing is, is this behaviour the correct one (I think so) which means that previous drivers with or without the option checked would cause loss of data if power was cut/lost.
(the old ones performed more or less the same and they shouldn't)
The new driver really flushes data beyond any earlier version, still, the wording of the two options doesn't realy make sense.