In my opinion, the compaction of sand is hunka-bunka. To properly compact it, one would have to tamp it down.
As for stifling plant roots. Just don't see how. Sand is pourus, even when tamped down.
Got play sand in one tank, and the swords have a root system a good foot long.
Have paver sand in the other tank. It has slightly larger grains. Only stems, but great roots. And no bottom dwellers to stir up the sand and no anaerobic pockets.
As for gray sand, I have seen dyes, but they were for brick mortar. Can't say I have seen gray sand though.
And about the poo, easy to clean. Another way to stir it up is rubberband a chopstick or piece of dowel rod to the siphon hose. As to going back to gravel, well one day I might set up a ten gallon to mimic my very first tank I had as a boy. Red gravel, three ceramic soda cans, a bubble filter, and a couple of clumps of anacharis. Other than that, gravel is for the driveway not the aquarium.