I've used the K10s in a good-sized room, and they really rock -- I used a pair of them as mains with an older Mackie 18" powered sub. The K10 acts like most everyone elses 12". But, they're heavy and expensive. If the Mackies are half as good, though, they're probably a great choice.
I just loaded my car (Hyundai Elantra Touring) for a sound gig tonight. Two Peavey 15" mains, two subs, four small monitor wedges, amps, cables, etc. I'm gonna need to get a bigger car!