im using the 4k step guide, so all of my settings are what step recommends for 4k, i use all optional mods too. i do however use enb performance instead of heavy because even with my ryzen 5800x, 32gb ram and 6900xt i still get like 30-45fps on heavy whereas performance looks great with much better framerates.
embers xd comes with a couple of drawbacks. one is the look can be extremely inconsistent with the rest of the game, more noticable in helgen during the dragon attack and windhelm in the civil war questline. disabling embers xd has made the game look acceptable while retaining a more vanilla feel.
the other drawback is looking at some light sources can cause the game to go into slideshow framerates, which is why i had to uninstall it. i'm not sure what caused the frame dips, i didn't see anything in the guide that would fix it, but help on that would be nice. i'm still going to keep it uninstalled because it makes some scenery look really out of place.
while quickly speedrunning the main story to check if all that worked, i had to look up why irileth didn't appear for dragon rising, and realized the culrpit was "not so fast." it turns out that isn't so much a natural fix for the pacing of the main story, but more of a timegate. the problem i have with it is it doesn't let you know "hey come back in 6 days"
i guess if you have the mod you're expected to know it already, but i think for STEP that should be avoided since it can cause confusion and doesn't really change the quests to naturally have better pacing, but just adds an artificial timegate to stifle progress in that questline, making it inconsistent with the vast majority of the game.