When I vac the tank as long as I don't touch the sand with the vac it's pretty easy to clean.
Aren't you worried the sand will go anaerobic, if you don't deep-vac it?
I think that's what happened with one of my tanks. I put a top layer of nice, smooth-grained filter sand on top of the existing gravel. It looked so pretty, that I didn't want to disturb it, so I didn't do my usual, weekly deep-vacuuming, the first week. In the second week, I had an outbreak of blue-green algae, that supposedly comes from lack of oxygen.
The other problem I've had with this fine sand, is that it jams up in between the two tubes of my Lee's adjustable height gravel vacuum. That makes the vac almost impossible to take apart for adjustment or cleaning.
So from now on, I'll be deep-vacuuming the sand (now completely mixed in with the gravel.....looks wierd), and I'll be getting a one-piece vac.
Oh yeah, one other problem with fine sand. There's always some extra fine sand that gets pulled into the bucket, and you have to dump that outside, not down your sink, if you don't want your house plumbing to plug up.
As for a smooth dark sand, other than black, I haven't found any yet. Dark brown would be really nice. I really don't like the look of black; it looks so un-natural to me.