by RonPurewal Sat Jul 26, 2008 2:43 am
my two cents:
in my reading and observation, i have seen 'far less' used almost exclusively as an ADVERB, while 'much less' is widely used as either an adverb or an adjective.
so, the above sentence ('far less time') violates that principle, and so MAY be considered unidiomatic. again, i don't work for gmac, but that's my take (and i read lots and lots and lots of formal writing).
on the other hand, you could equally well see either of the following:
i work out much less than i used to
i work out far less than i used to
i prefer the second version, but i'm pretty sure that either is acceptable.
i would reserve any judgment on this matter, though, until there is evidence from official problems.