How does your DS tend to play with his Legos now? Does he only rebuild the kits, pretty much following instructions? Or does he do a lot of custom creations? Is he spending a really long time looking for the perfect pieces, or does he not really care if the colors match? Is he in charge of putting them away, or is that something you help him do?
For my 6yo DS, who has perfectionist tendencies, we kept kits in labeled gallon-sized ziploc bags along with the instruction booklets inside the original boxes (he liked studying the pictures) in his bedroom, b/c he was pretty much just recreating the kits for a while. Finally, after about a year, he loosened up when he realized his building would go faster if he wasn't so insistent on having a particular color. And his creative/free-play with the Legos exploded (which also coincided with an increase in the number of kits he had).
I've always helped him pick up the Legos (he'd be happy to step over them all day; me, not so much), and since I had been an active participant in helping him find pieces, I insisted on a bit of organization. This has worked well for us for almost 2 years. I divided the regular bricks by color, and put them into pint-sized ziplocs, which stay in a medium-sized tub on our coffee table (which is exclusively devoted to Legos since it's a good height for DS). However, DS has lots of non-brick pieces, so I bought some organizers for those. The thin base plates go in one semi-transparent, hard plastic pencil case (I've bought some at Target, some at WalMart--we've got 6 now, and they stack nicely); the car parts go in a different colored pencil case; the minifigures and their accessories go into yet another pencil case. I also ended up buying 3 plastic cases from the craft store/beading area that had lots of little compartments/divisions inside. One of them has frequently used pieces, divided by size/shape: two-peg smooth, four-peg smooth, small square smooth, cylinders, etc. Another divided container has less-frequently used parts such as fire, single round pegs, clipping pieces, etc. Every now and then, DS will be overwhelmed with putting away his giant mess of Lego parts, so I'll sit down with him, separate out all the pieces, and put them back into their caddies. Takes about half an hour, but it's so much easier for DS to find what he's looking for that I'm happy to do it.
It would have driven both of us crazy to have all the pieces in a huge tub...but if it would work for you/your DS, go for it!