Zane, I'd like to add as I cannot post pics yet. I can say though that I can fit my mamiya 6 MF into the Orion AW hip back that has the detachable top piece to turn it into a full back pack.
This bag will hold my M6 and all lenses, PLUS my Hassy with WLF, 80mm lens, and back, plus a spare back, my lightmeter, AND 15 rolls of film!!
I carry my additional blad lenses in lowepro lens cases inside the top of the clip on back pack along with filters, cable release and additional film.
I was amazed at how compact and easy it is to carry both systems.
For size comparisons, there is no question the M6 has the smaller footprint and smaller lenses overall. That alone makes the M6 the way to go for portability and convenience, but the blad is a lot bulkier, and is really a tripod use camera. That's not to say others should not use it handheld, I just personally don't find it intuitive to use that way like my M6. That's why I have both. Spares and a good used market is a good plus for the Blad system also. The M6 cameras are getting more rare, and are commanding very high prices. That might be one reason you want to swap systems, but if I could persuade you to keep both systems, I think you should, it's worth it in the end IMHO anyway.