IMO about one's bond allocatons? Good Luck! It's a complex game and nobody, not even the great Bill Gross of Pimoco knows.. Every type has it's pro's and cons and Ups and downs.. and It all depends on what your Tax situation is and a list of 5 other issues before even attempting to figure out what "might" be best for you and it's still a guessing game and ask everyone else and they will have different approaches. and this is way beyond Investment Basics...
I would go to > M*Retirement Discussion Board and ask them in there.
People like Bob Brinker's 50/50 port #3 advocates
20%VFIIX,10%VIPSX and 20%VFSTX
A Fixed Income Port of
40% VFIIX, 35% VFSTX, 10% VIPSX and 15% VWEHX
While I own Balanced Funds and LSBRX and reserves in VBIIX and don't auto invest Divs & CG's, but do so myself, after I pay the taxes and Take out what I think I will need..
Good luck!