Great summary! Thank you.
I have a Horizon and a Shu-ta as my only metal throws. I agree with your assessment. The Horizon is really long spinning and stable, but I find myself going for the Shu-ta - it just feels nicer in the hand even though it will de-stabilize well before the Horizon. Of course, for fingerspins, I always use the Horizon, and don’t mistake my comment to mean the Horizon is in anyway sub-par, it is just the Shu-ta feels more natural in my hand. At my level (intermediate - advanced), I can do most of my tricks equally well with either. The Horizon spins longer, but (for whatever reason) I seem to catch the string better with the Shu-ta when learning. YMMV.
I also got a Protostar yesterday (as part of a pack) - I wasn’t expecting much from a plastic yoyo, but wow - I was really impressed. It seemed surprisingly stable and usable. Quite the contrast to my Velocity - which has cool dials which I use depending on my mood, but is not a very smooth throw IMO.