In line with Silas' comment several companies now have a "Bluegrass" package of strings where they essentially use light guage for the top 1,2&3) strings and medium for the three low strings - creating a sort of medium-light mix. Supposedly since the base strings are lower tension it is of less impact on the guitar to use a heavier guage for those. I've tried several sets for some particular guitar/miking/acoustics situations where I needed to get more boomy bass volume. A Luthier once recommended a mix like that for a beat up light weight guitar I had that needed a little more bass but didnt have the structure to handle medium strings all around. I have a set of John Pearse Bluegrass mix on my D-28 now because I use it mainly for Bluegrass and like the sound difference it creates between the bass and treble, and it helps me get a bit more bass volume on that particular guitar without having to pound the bass so hard - gettin too old for that. However my other guitars that I use for old time, blues, rags and finger picking have standard sets on them - but then they are easier to play and don't need any bass boost.