I'm sure a lot of people would disagree with any claims that the KaBar is cumbersome in a fight, it's been killing America's enemies and doing it quite effectively since 1943. I'm not quite sure where you're getting your information other than your personal bias against the bowie design, which is fine and really all you had to say, but to say the KaBar design would be in any way ineffective is proposterous. The KaBar is time proven in fighting scenarios.
As for it being hard to remove, stabbing and removing anything into living or once living material, takes a good deal of strength no matter how small and thin. I got a 1 1/2 inch finishing nail stuck really deep in the muscle of my upper arm once and even that took a real good pull to remove. I HIGHLY doubt it really would make a noticable difference to a tough, physically fit commando.
I did not really intend to get into an argument here, but almost all of my knife-fighting background is from the Fairbairn school, and a handful of fighters I know who train using Fairbairn-style knives and principles. The Fairbairn-Sykes knife is a fine example of a modern knife
specifically designed for killing, with no concessions made for any other function. The Ka-Bar was designed as a multipurpose field, survival, and fighting tool, which is evident in its appearance, construction, and actual use.
The F-S was selected and issued to several British commando units (including SAS, probably the world's most talented killers at the time) and OSS/CIA (who used them solely for murdering people in devious and creative ways). Because of the Fairbairn-Skyes knife's purposeful design, wide popularity, and frequent issue to killing-specific personnel, I understand that in the 20th century there were more people killed by the F-S than by any other individual knife, including the Ka-Bar. That figure probably is even more dramatic if you include other Fairbairn-inspired knives, like the Gerber Mark II and the Ek series. I wish I had a statistic to show you, but unfortunately I don't.
The F-S has a delicate, highly pointed tip designed to pierce skin and clothing with the least amount of force. The Ka-Bar has a thicker, curved tip. The F-S has a triangular "wedge" shape and diamond cross-section that makes it easy to penetrate deep and even easier to pull out of tissue (resistance actually
decreases as you pull the knife out). The Ka-Bar has a straight, flat, modified Bowie shape that does not significantly increase or decrease resistance in a stabbing attack. The fuller is
not a blood groove, and it does not make the knife easier to withdraw from tissue. The F-S is double-edged and symmetrical from both the front and side. It can be drawn and used in any grip, without regard for orientation. The Ka-Bar's Bowie shape requires the knife to be oriented properly before it can be used.
I suppose the differences between the two knives is most evident when you consider who uses them. Fairbairn-style knives are issued to and chosen by professional killers- OSS, CIA, and commandos whose sole use for a knife is to kill people. The Ka-Bar is issued to Marines and soldiers, who need a knife that is not only capable of killing, but also has a multifunction shape for various cutting tasks, and durable construction for prying boxes and batonning wood. The Ka-Bar, out of necessity makes compromises to be a better, more durable all-purpose knife, and it is excellent for that purpose. The F-S will be destroyed if used for anything other than stabbing- but for the specific purpose of killing people, there are few modern knives that can do a better job.