For me, the mamiya 7 is the fastest non-interchangeable-back loading. Compared to other cameras I've used, the spools pop in and out very easily. If I'm out with the hasselblad and shoot multiple rolls of a couple of film types, I'm not going to carry multiple backs for each film, so eventually I'll have to reload a back, and it may not occur at the most opportune moment... So loading speed is still a factor for me.