I shot a lot of fashion with the RB in the 90's, much of it handheld with the L-grip and 180mm. Sure, it wasn't like shooting an AF Nikon with a motor drive, but when you wanted those big negs, it was dynamite. The RZ would have likely been a bit better fit back then (the motor drive is much better). But I still use that thing - just returned from a USA to Scotland to Geneva trip and took the RB with a 50mm in my carry-on. Wasn't the lightest backpack ever, but worth the extra weight.
But these discussions get kind of tiring, don't they? A camera suits you or it doesn't - every single camera bears some sort of compromise you have to live with.