Not quite as systematic as you suggest... but I'm fairly convinced that my issue is with dips, the eccentric phase in particular. Bench presses or pushups never seem to irritate my shoulders. With kettlebell overhead presses, I certainly have to keep an eye on fatigue, but they dont seem to cause the same kind of soreness in what I think is the anterior deltoid that I was feeling yesterday. But with dips... I've been trying to do lighter regressions using bands, and it feels like that has helped... but it also feels like they may be wearing me down anyway.
Plan is to drop them completely for a while, and see if that makes that feeling go away. I've been stubbornly trying to keep working them in some form, since it seems like an important skill for obstacle courses.
Have never had any shoulder issues with TGUs. With the TGU, the soft spots have either been at the pec during the roll to the elbow (which I believe is a function of the fact that I spend most of my day hunched over at a computer), or wrist fatigue. But the static lockout of the shoulder has always seemed solid. I do some daily handstand holds against a wall, that similarly has never been a problem for the shoulders.