you guys are kinda picky man... doesn't even make sense to compare a $5000 snap-on tool box to a $500 one. if you want to make comparisons, at least pick something in the same league... like a ball-bearing craftsman or something. it's like going to a VW dealer and telling the sales guy "damn, this jetta just ain't no ferrari is it?"
personally, i've had that 72" one for over a year now fully loaded probably with 300-400 lbs worth of sockets/ratchets/and various other tools. the wider middle drawers are wide enough to accommodate a 25" breaker bar so I have no complaints. the little compartment to the right at first seems pointless, but then i found it a perfect place for special tools that come in their own molded cases. as for 18" depth, well... anything in this league is 18" or there abouts... seems to be a standard depth size for boxes in this category, but I do admit that as I'm using the workbench top more, i do wish it was more like 24" or 30"... but that can be replaced easily for $50-ish with a slab door or something if it really bothers you. as for the drawer slides not being full-extension slides.. that's true, but it's not that bad... the 1" at the back hasn't prevented me from putting my tools all the way back there. the other "negative" i can think of are the 2nd from bottom drawers being only single slides on each side. the bottom ones are double slides and can hold a lot of weight, i've used it as a step to reach something high up so no problems with my 180lbs. but the 2nd from bottom are tall enough that you might put something heavy in them but you can tell it's pushing the limits at around 100lbs of weight. i might consider adding a 2nd pair of slides or upgrading the existing ones to something heavier duty. i don't roll it around much, but the casters are awesome and very smooth even with everything i have in it right now. anyway, for the $499 that i paid for it over a year ago, it was worth every dollar.
i have considered a smaller cart to roll down the street when my neighbor needs me to go over and help with something... that kubota looks interesting, but wish it was actually designed by kubota; seems like it's nothing more than a generic box that licensed the brand...