Jake said is perfectly. lol. I am in the position of my Netlea soiling leeching nitrates, so I wanted to tear down my tank and redo it. I am moving in less than a year, so I called around looking for it. Couldn't find any, nearest aquasoil place is 2 hours away, so went a different direction all together. I was willing to use it and some peat and IAL's and RO water for 6 months or so until I tore down and moved and start building my dream rack, but not for long term use.
As for the stories, you have to take them as you take any bad review online. I look at it like this, I fixed XBox and PS3's for a living, run my own business doing it. If you look online, you will forums with tens of thousands of people complaining about how their 360 or PS3 died after a year or they are on their 5th console in 6 years, etc. That's probably, true, there are some crappy ones out there. But when you take those 10,000 people compared to the 100,000,000 consoles sold, it's a rather small number. Most people only go online to complain or when asked something directly. Not many people make a post saying hey, my Xbox is running fine.
I see the Fluval Shrimp soil thing as sort of the same thing. Could be thousands of people out there using it fine, but the ones who don't have luck with it, are going to go online and complain.
The biggest problem is there is no way to know if it's the soil, if the person is new to shrimp keeping, their water, their params, etc. When I used it before, I was a noob. I used tap water with it with high ph/kh/gh, so hard to buffer, I changed water all the time, vacuumed the substrate, and about every other noob mistake. Now, I'm confident I could have made it work, at least for the short term when I needed it, but couldn't find it locally.
The biggest thing is doesn't seem to super buffer like some soils. My Netlea can get the pH down to 5. No way FSS would ever do that. Is that needed though? Can caridinas get my in a 6.5 or 6.8 tank? That's a whole different thread for debate. lol...........