I have a Lowepro Rezo 160 (or is it 170?) that I pretty much loathe. I bought local, cheap, and available when I got my camera and I shouldn't have. It works fine and holds most of what I want it to, but it's bulky, boxy, and ugly. I can fit the camera, the 16-50 and one or maybe two very small primes. Add in some extra junk like a battery, lens pen, etc., and it's full. If I take just my primes, I could probably carry the camera with 3-4 small ones.
I actually happen to own at the moment, though, a Domke f-5xb. It's still brand new with the tags and is in my car waiting to be returned to the store. I'm doing a little shopping around to find stuff to add to my holiday wishlist for my wife and kids, and I just couldn't tell if the bag would meet my needs or not. I can comfortably stuff the K10d, 43 ltd, my vivitar 28/2, and my K55/1.8 in there with room to spare for another lens or two. I was even able to put the 16-50 in there with the hood removed along with the 3 primes. I could have easily added a second battery, spare SD cards, a lens pen, and some other odds and ends (my front pocket wallet and iPhone fit in the main compartment outside the padding) and still carry it comfortably for a day. Should I ever scrape up the cash to upgrade my body to a K-5, it should fit even better. I think I've found my light kit bag, once I return it to the store and ask for it for it for a gift.