I will hear some in my filter every so often, I just take out the impeller and syphon the little bits out with an air line. I actually like sand.....
Pro's:
Looks better IMO, I find it eaiser to clean because my cories help stirr the debris up and then the filters will catch it, some fish LOVE to dig and burrow in it.
Con's:
Its messy, some fish will be hard to remove from the tank(if you ever want too), some fish will move it around, if you get the wrong kind it can cause algae and possibly be too coarse on some burrowing fish, sand also needs to be stirred every so often. But having burrowing fish and MTS, and thinner layers of sand will help aleviate this.
I have a 75g with gravel and a 55 with sand. I personally prefer gravel for ease of use, BUT if its a planted tank it is absolutely a blessing in disguise, because it makes it MUCH eaiser to plant and/or replant. All in all if you dont have burrowing fish, dont want to invest a little extra time during cleanings your tank isnt planted...just go gravel. Another thing, I personally wouldnt mix sand and gravel....for many reasons.