One of my tanks is all gravel, and the plants do just fine. I have some tanks sand, some floramax, some a mixture of sand and gravel. If you get stem plants and no heavy root feeders, gravel works fine. But cories do like sand better. If you want to switch, you can just scoop the gravel out during a water change and carefully lower the sand in cup by cup, and it won't cloud the water up too badly. When I refill my sand tanks, I either pour the water through the floating mesh tube, which breaks up the water flow so it doesn't kick up sand, or I am the water flow directly at the tank glass which does the same thing. I don't have any more trouble with the sand tanks than the gravel ones.
Bettas: Roland, Belle, Snow White, Polo, Elise, and Titan. | 120 gallon community tank | 55 gallon angelfish tank | 20 gallons of guppies