You can't just classify blades' roles by their size. I've split logs 4-6 inches thick with my less-than-3-inch DPx HEST. Blade thickness, shape, ergonomics, grind, steel etc should all be taken into account. I believe that an ideal survival tool should be able to take rough use in dire circumstances, and be easily maintained in the field, so I tend to favor quality high carbon steels (between RC52 and RC59) for both my designated rough use blades and my slicers. That's not to say I haven't used stainless knives for extensive outdoor use... a Mora 860 or Cold Steel Finn Bear can be super performers, and AUS8 is one of my alltime favorite outdoor use steels. I just don't believe these high end, hard brittle stainless steels serve much of a practical role when it comes to extensive outdoor use. I firmly believe the simpler the design, the more tasks the blade can perform. Simple spine, simple belly, simple grind, simple point... I have blades ranging from 2 inches to 16 inches that I would consider practical survival tools. Thankfully I have a go bag in the closet that sits packed with multiple blades for multiple roles (and maintenance kit), and ALWAYS have a HEST and Victorinox Spartan on me.