I've never used storage boxes for litter boxes, but I have thought about it.

I have used pine pellets though. You scoop out the poops and the urines dissolves the pellets into sawdust. Since the pellets do not go through the scooper's holes I would dig down to bring the poops to the top, drop them off the scoop and then scoop only the poop up with a minimal amount of pellets. (hope that made sense)

I also found that if you want to get rid of some of the sawdust before you actually dump the whole pan you can do this:
Take a scooper full of litter but instead of shaking it over the litter box, shake it over your garbage bag. The sawdust goes through to the garbage and the whole pellets stay in the scopp and can be placed back into the box.

My primary litter though, is SCOOPABLE pine! I like it because it is much lighter to carry than clay based. (both bringing in the fresh bags and taking out the used clumps to the garbage). And (as long as the cat covers) the odor control s quite good. But beware, it does track out of the box.