I just had to add sand to one of my tanks, and yes, it took about 2 days to settle. However, the plants Tabby has aren't really root plants anyways, at least the anacharis definitely isn't. They would be really simple to re-plant. Plus, I can say that the cloudy water, while unattractive for a few days, is perfectly safe for fish to live in. Having two ten gallons ATM and looking to get a 40-60 gallon once I move means figuring out how to do things on the cheap! Plus I consider them kicking it up part of that natural look. :)
Realistically, without root plants, sand might be a bit of a problem unless it is poked every week or so. The anacharis might develop some roots, but not enough to create a root base under the sand and in the flora-max. Plus, once you cover the flora-max with sand those nutrients will pretty much be trapped under the sand, which would be fine (ideal actually) for root plants, but not so great for the ones you have. You will either need to add ferts for them, or just watch to make sure they don't start getting scraggly. A nice amazon sword would work well in your tank and actually benefit from the sub, as would chain swords, wisteria, or vals. Crypts are less hardy and more slow growing, but they are a favorite of mine.
Remember that the tank your fish lives in is his or her's whole world. Ask yourself this question, and answer it honestly: would you choose to live there?