Versatility/flexibility/options and weight are two categories that come to mind for discussion on this topic. First, we talk a lot about multi-use tools, and some on the forum wouldn't even consider carrying a tool unless there were at least a half dozen things they could do with it. The other side of that coin - maybe you need more than one tool (knife) to do all the possible functions for which it was intended (or not in some cases). It's clear from the postings on this topic that there are many functions that are best left to a "knife". (Of course we all knew that.) It is also clear that some functions would be better performed by one type/style of knife over another, which brings me to the second category. Knives for any reasonable survival use should all weigh less than a pound. So let's not limit ourselves to too few useful tools by thinking that an extra pound may be the difference between life and death. Carrying one good folder and one good fixed blade knife should be SOP. Maybe a slightly larger BOB is in order.