Jon, does that Sirui bag genuinely handle a DSLR and four lenses?
I've got a fairly generic Incase messenger-type bag (the only type I like) that carries my D7100 and three lenses (Nikon's bundled 18–105mm, its 105mm macro, and Tamron's 70-400mm). It's 17" long. The Sirui falls short of 14" and that photo makes it look like the only way four lenses are getting in there are by stacking them on the sides. (Not feasible with any of my three lenses.) I gather the camera has a lens attached, but I'm still not able to figure out how four would go in. (I typically don't attach a lens to my camera until I'm ready to shoot.)
Thanks for any thoughts, and for that matter if you think any of these bags could handle that mix of equipment, please do let me know — the Incase is adequate but I've been ready to upgrade for a while.