The POGs use the second expression as reference (https://twiki.cern.ch/twiki/bin/view/CMSPublic/SWGuideMuonId).
For what I could tell, the difference is negligible (I think it is basically trackIso vs chargedHadronIso, http://cmslxr.fnal.gov/lxr/source/DataFormats/PatCandidates/interface/Isolation.h?v=CMSSW_5_3_12#010 ?) - but to be 100% correct, the good one is the one Austin just wrote. 
So... why not change?