I used 12 gal recently and the returns get clogged too easily. I'm almost filling the 27gal as it is, so the 12s was just an experiment.
There is a big advantage. Less pH and EC swings with more buffer (water).
A 5 gal bucket only holds 3 gallons since you don't fill all the way up as cannabis likes a dry stem (no stem rot). A 27gal tote holds 13gal.
I use bulkheads and they are easier to keep leak free on flat surfaces vs. round (buckets).
But mostly totes are better for the swings.
In veg 5gal buckets are fine, but in flower the pH and EC adjustments are a daily struggle. I can go a few days without checking my pH and EC with the totes and be fine.
Advanced nutrients work, but so does every other base nutrient. In a competitive market why pay more than you have to? I use cheap nutrients. They work out to less than a penny per gallon. I know people who are small time and drop $400 a month on advanced nutrients.
25lb of Jack's 5-12-26 is $45
25lb of CaNO3 is $30
5lb MKP was $15
8lb bag of MgSO4 at Walmart for like $5
I spent $100 on enough nutrients to do over 5000 gallons and that was shipped.
For the record I wouldn't be bragging about how much weight you push. It's the loudest one in the room who gathers the most attention, remember that.