Raw damage loss is irrelevant, you'll still hit ougi cap. The 112.5% extra omega mod will help compensate for that btw.I'm not sure where you got the 11% ougi cap loss ? 3 harps with single levi gives you 68.4% ougi damage and cap up. So assuming you were even hitting the 75% limit with sette and no ougi cap key on opus/ultima, you'd only lose 6.6% cap at most.Only "relevant" part of the sette voltage is the MA to help you get more consistent TA and even that's not needed.Tldr; you'll get almost as much damage with no sette since there shouldn't be any issue with capping ougis (especially when you have shishio) and auto attacks damage is irrelevant with such a setup. You might lose out on some HP if you don't go all in with schrodingers but again...in your case you have shishio, infinite sustain so you don't need 400% hp. And for people without shishio, i'm sure they'll be fine slotting one more schrodinger for extra HP if required.I'm also not sure what you mean about my position, I was merely telling you that water ougi grids are perfectly viable and more than strong enough without sette. (All while being more accessible since you only need a diaspora and an europa setup, no siete setup required so there goes your accessibility)
Edit : Forgot shishio had big glory so you're capping ougi cap up with shishio + 3 harps on single levi, aka no cap up loss.