Just a thought (although the post Eivindm gave is really helpful) I don't think a hive can have enough brood and 10 frames offer another 8000 or so cells of brood. Times that time the months a year your queen lays and you have a rough count of the EXTRA workers your hive can have doiing duties and going ito Winter.
Now... That said, if you look at the queen rearing and other video links page at http://www.beemaster.com/beebbs/viewtopic.php?t=2098
many beekeepers are using the TENTH frame as a DRONE FRAME - by removing all the comb and just installing a hollow frame, the worker build up the frame to accomidate drone cells WHICH attract varroa mites better (in concept at least) than do worker cells.
Either way, you have 10 frames in the brood box. I don't see the need for extra room for capped cells in the brood box, but haing a deeper cell in the HONEY super can be advantagous to many beekeepers.
It is much easier to uncap a frame from a 9 frame honey super than a 10 frame honey super - the comb is extended out and allows for a uncapping knife or other tool to better scrape EVENLY the wax cappings to allow you to better get at the honey.
But in the brood box, I'm a ten frame guy. This of course from a humble beekeeper who has only 2 hives and not dealing with anything larger scale than that. Good luck and read all the posts - check out those videos too if you have not, they are VERY informative and I love the bee boxes they use in the vdeos - try tilting these Langstroths like that and see where it gets you :)