Johannings knives are both very strong and tough due to the geometry (sabre grind on decently thick stock) and high impact toughness inherent in the choice of steel. He uses A8 which is a shock resistant tool steel, and one of the toughest currently used in cutlery. To put it in perspective, Johanning doesn't think A2 is tough enough for his knives.
Striders knives are strong due to the high hardness and stock thickness, but are not very tough and will crack at low angles and suffer fracture propogation easily.
The Becker Knives are no where near as durabile as the Swamp Rat, the steel simply isn't very flexible, and breaks easily under low angles. However it is decently tough, not as tough as the differential temper makes the Swamp Rats, but far tougher than the "high carbon stainless" knives.
Mission Knives, MPK-Ti has a high impact toughness and resists fracture from hard contacts and holds up to prying very well, however the edge is soft (~47 HRC) compared to cutlery steels and thus will suffer more impaction (but little fracture) if whacked against something hard.
Burke and Fowler both restrict their knives against cutting bone, a restriction that blades like Swamp Rat and others do not have. They are however very flexible.
In general, most of the high quality forgers make blades that are very durable in respect to bending and hitting the spine with a hammer, but the edges are a lot more acute (~10-12 degrees per side) than most of the knives mentioned in the above and thus will not handle hard impacts as well. Generally though fracture will be minimal, just impaction. Of course you could request a custom with similar edge angles, 15-20 degrees per side.
The HI khukuris are tremendously strong because of the stock thickness, and very tough because of the differential temper. The only weak point is the handle, it can not take the heavy amounts of abuse that some of the above can.
-Cliff
