Get a Domke insert.

http://www.bhphotovideo.com/bnh/cont...ughType=search

I carry all my cameras, although admittedly they are not SLRs, in one and stick it in whatever bag I'm using. They are just open squares made of nylon with padding in the sides and some velcro on them to be used in Domke's photo bags to organize things. However they work fine on their own. I have a single pocket inset, but you can get them with different arrangements of pockets and different heights. The only problem is that they are not padded on the bottom which is easily solved by cutting a mouse pad to fit and sticking it in there. The advantage of the insert is that you can grab your camera quickly and actually use it.

The single pocket one is very versitile. I've used it for a Rolleicord, a Leica, a Mamiya 6 and a Pentax MX (that one is a SLR). The all fit and the weight of the camera keeps them from falling out so the fact that they don't have any top really isn't a problem. You can also easily stick them in a suitcase or backpack when traveling.