EDIT: And just for clarification... unlike the 1.2.2a package where MOBS for Oblivion and MOBS for SI are separated into two individual files, the MOBS SI.esp from BFG99's MOBS 1.3 package actually includes stats for both games, so I only need to use BFG99's MOBS SI.esp and nothing else, correct? I assume this will change whenever CorePC finally integrates BFG99's changes (so it'll be back to 2 files) but for now... if I just want to use MOBS 1.3, I only need to use one file, MOBS SI.esp. Is this correct?
Just to clarify, that is correct. Once CorePC approves the 1.3 version (if he ever does

), I'll create an Oblivion-only version for players who do not have Shivering Isles. The idea, then, would be that only one file would be needed regardless of your setup.
The currently posted version of MOBS 1.3 needs one small tweak: it includes two new weapons which Bethesda probably meant to add but forgot to do so. These weapons prevent MOBS from being added to a "Stats Only" bashed patch, though, so they will be removed from the final version.