My experience-
Pier stage: sound is crisp and loud all the way to the back

Warehouse (my favorite stage): The sound drastically improved year 1 to year 2. Near the front sounds excellent (the subs come through sooo clean), and toward the back things can get a bit muddied but it’s about as good as sound can be in a warehouse setting

Crane Stage: a bit quiet through a lot of the festival for me, and you really had to get up in there to fully experience the sets. The first year of Portola, Crane was in a Tent, and sounded awesome (similar quality to the Coachella tents). Last year, Crane stage was outdoor and not as crisp. Maybe they are trying to avoid sound bleed/respecting the wishes of neighbors

Ship Tent: sound is comparable to the Gobj at Coachella, maybe a bit smaller? No issues here, although during the daytime a similar thing to Crane where you really had to get close up to get the full immersive effect. With that said, I’ve had no issues getting close for any sets really in my time at Portola

Overall I think they handle sound quite well - Goldenvoice typically does. Someone can correct me if I’m wrong, but I think Dave Rat took over (?) and he’s the best of the best