I might not have understood you 100%, so bear with me if I'm totally off here, but I guess you are thinking of using those drilled sprockets that you bolt onto the hub as if it was a diskbrake rotor, correct?
The problem I see here is that you have less choice as far as sprocket goes. Less variety in teeth number, and practically non-existent 1/8" width (only 3/32"). Also, those sprockets are quite a bit more expensive than thread-on.
However, this would be about the only serious disadvantage I can imagine. A sprocket bolted with 6 M5 bolts onto the hub should be a ****ing solid setup. It sounds so good I'm kinda thinking of going this route myself.
Hmmm....
Oh yeah: slight disadvantage: you won't have a flipflop wheel - but you probably won't care anyway, since replacing sprockets this way will be easy and quick. Other slight disadvantage: no freewheel support. Can't help you with that one, mate
Edit: actually, there is a solution to that problem: get one of those singlespeed hubs with diskbrake support. Bolted sprocket on the fixed side and freewheel on the other, and there you go. This kind of hubs aren't as cheap as a conventional freehub though.
Edit 2. heh... OK, so then it came to my mind that there are kits made by Surly and others, that will transform the freehub into a singlespeed. They are rather cheap, so with a Deore disc (non-centerlock, mind you) hub like the M525, and one of these sets, you should have the same functionality as a flipflop hub.