I've got Caribsea flor in both my 20 gal cube and my 77 gal display. My yellow watchman goby and pistol shrimp sift through it all day long in my cube and I have a twinspot goby that sifts through it in my main DT. They don't seem to mind. From what I've read anything 1-2 mm is good.

2"-3" sugar sand in 144G with 2 MP40's and a MP10. I used to have a little bit of sandstorms but with some playing around with the positioning of some rocks and the vortechs it's no longer a problem. And no dead spots.

It all boils down to whether or not you are running a shallow sand bed (less than 2") or deep sand bed (4-6"). For a SSB, you want more coarse sand that you can siphon if necessary. The Seaflor is great for this and allows sand sifting fish to accept it.

For a deep sand bed, you want to use Sugar size or oolite sand. You do not want any sand sifting fish in this setup. Some Nassarius snails are great in this case to mix up the top layer of sand. It does settle down when the bacteria colonizes and weighs it down. Still, in a high flow area, it will have a tendancy to blow around.

I ran a DSB in my 75G with very good results. Only problem is my 75 is fairly heavy stocked and ended up with some Red Slime. It is very hard to siphon anything out without making a mess. So, with my new 180G setup, I went with 2" of Seaflor Select so siphoning can easily be done if necessary and be able to keep some sand sifters. I also have a remote DSB plumbed into my system to use the benefits of that and if any problems arise with it, I can easily take it offline and not have any ill affects on my display tank.

Crushed Coral
 

I had to cover my medium grade sand with crushed coral to keep the sand staying on the bottom of the tank.

My twin spot was the reason I went with a finer sand in my display tank. I was worried about the coarseness of the Aragamax Select. It is the 1-2mm stuff that I've got, and it is just so coarse. If yours can handle it, maybe I'll think about swapping it out. I do have some sand in the water column.

Am still using sugar size sand in my high flow SPS system. The system is 110 galling long tank w/6 power head 4 evo 4 koralia + 2 tunze 6045 modified + 2 clown fish + 2 wrasse. Does it work yes! Would I do use sugar size sand again no. I used it because I like the look!*
I do get the occasional controlled sand storm, but it never seem to bother the SPS, I always have full polyp extension even with the sand storm.