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There are so many variables at play. Differences in yield shouldn't really be compared unless it's the same strain and even then its a crapshoot. Some strains are higher yielding than others. Light/Environment can be very different.
Get everything dialed in and grow out a couple of crops of the same strain to give yourself a base. Use Blumats if you can to eliminate the watering variable and make your life a lot easier.
If you're going with 80 gals of soil I'm betting you'll be recycling/no-tilling it. Some amendments may not fully break down the first cycle if you haven't had your soil sitting around for a while so don't worry too much if it's not the most amazing plant you've ever grown. The soil will get better with time and so will the plant growth.