It's been about a month since in a 10G I put plain top soil, a bit of sand, and topped it off with gravel to
help hold it all down during water changes...and the usually slow growing Java plant has grown much
bigger than is normally expected! I swear it looks about 2x the size! :) I also use a drop of Flourish
once a week. The crypts are going nuts too.
I will definitely redo all the tanks to a soil base & highly recommend it!
The only "con" is during changes, it does all cloud the water a bit unless you pour really, really slowly.
It's getting more brown algae than non-soil tanks also.