My personal experience has been that buried wood performs better than just mulch. I mulch my buried wood beds also. Plants in soil which was only mulched did not grow for me during our past droughty summer.
I've been trying to convey to my dad that while this method is good, it's not the best out there, and that hugelkulture and more diversely composed sheet mulches are good tools to use as well. I wouldn't say that one is better or worse, but I wouldn't rely on one or the other entirely. Maybe try some "back to eden" beds and some hugelkulture beds, and see which ones work best for your climate/soil type, and then you'll know for sure!
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