Well, here's my hybrid... after a couple of years of chasing tools between the upper 3-drawer roller, a 4-drawer portable chest, and 3 smaller hand-held boxes, i finally bought the 8-drawer roller yesterday.
Rather than bin my 3-drawer (i'm SEVERELY low on space), or spend $$$ on a new chest, i persuaded the 3-drawer to fit on top of the 8-drawer with a little help from a BFH. I'm not all that happy with it in retrospect- i should have just bought the huge combination set that Sears had on sale at Christmastime (i think a six-drawer roller, 3-drawer midsection, and six-drawer chest all for $300), or else replaced my workbench with something with a few sets of drawers. With this setup, the most convenient section is the huge opening in the middle, and all the drawers are either too high or too low. Bah. i also lost valuable putting-junk-on-in-mid-project space, since anything i put on top is pretty much out of sight.
Well, you know what they say... live and learn, then spend some money on tools, then learn some more, and spend some more money on tools, then learn some more...
...dave