I would welcome a 91mm knife without any back tools. After carrying Alox knives and also 84mm knives without a corkscrew I've developed an appreciation for knives without back tools. Even if it is only 2mm that's still noticeable. Remember that a knife layer is 3mm and actually the saw is a little less than 3mm and that's including the tool and a liner.
All of the tools on any multi tool are a compromise but that's the point. You don't need to carry a bunch of individual dedicated tools just on the off chance you may need one. Having said that some of the back tools are really quite difficult to use. Their position in the centre of the knife almost aids in the tool closing when you're trying to use them. Having said that I don't really care. I know what to expect when I'm using them.
I would gladly buy a 91mm without back tools just because it something new and different.
