1) Probably the latter
2) It may actually be weaker in the former form, as canceling into a juggle may yield higher damage properties
3) It won't be OP either way because the initiation time will probably be so long that it can't be used for normal low punishes and must be reserved for low holds (just like standing Izuna). 12 frames or w/e
4) If you're caught by a low throw of any damage for low hold spamming then you deserve to die. Nothing OP about that
5) Izuna damage isn't super-terrible for a grappler throw (hold versions are a different issue). Just de-incentives low hold-spamming, something that should have been in there since the start. Baiting a hold of standing or crouching is theoretically the same, so the reward should be the same. More people spam lows though to duck highs and snag lows, obviously, so they can go to hell
6) The Yoko Izuna has the most generous, lax timing in the world. You have to deliberately screw it up to fail it. Thus, I don't see a big difference between requiring the semi-circle vertical and 360 spin directions after it or not.
