This is a great link on using mineralized top soil:
http://www.aquaticplantcentral.com/f...on-talbot.html. I personally would have tried it out if I knew this to be an option. After all, it is a pretty cheap method, if you don't like the results, you haven't spent too much money.
I do like the flourite substrate a lot. The only thing I have found with flourite is if you are planting a lot, you can sometimes unsettle the dust and the water will get murky for a few hours. At least, that is what happens to me.