Well running them in parallel IS bad... if you have no kind of current balancing. However if using current balancing resistors, there are really no issues with running them in parallel. For two locs it doesn't matter regardless of how you do it, since you'd still be in the voltage range of the P3 running them in series. However if you tried to run say.. two high power 405's in series, you might run in to problems.. Though i'm not exactly sure what the voltage ceiling is on the P3's without looking it up or asking drlava.