The numerous small contact points found on a serrated blade significantly increase the cutting force for each point of contact, since any given applied force is distributed across a much smaller surface area.

While serrated blades are somewhat more difficult to sharpen, the curvature of the individual scallops found on a serrated blade also provides additional strength/support at the blade edge, allowing it to remain sharp longer than a straight blade.

I can think of way too many survival scenarios off the top of my head that require a sawing action to ever consider going into the woods without a combo blade. There's a reason saws don't feature straight blades, no matter how sharp they are.

Jim