Most of what you have said is accurate, although there are a few things I disagree with.

That bigger man stuff isn't relevant; the issue for Pac won't be a size difference, but the fact Floyd is simply a stylistic nightmare for him, just as Marquez was [only the nightmare will be exacerbated by greater handspeed/upper body movement/reflexes]. In the same vein, it wasn't the fact Floyd was bigger than him that ruined Marquez in their fight, it was the fact he couldn't carry the weight [he became sluggish] and PBF was lightning quick at his natural weight. I think you're pretty much spot on about everything else, though, including the way the fight is likely to play out.