I want to point out an error in your description of the KE equation. It could be simple semantics but I feel clarity is best.
The formula posted is correct, KE = 1/2mv^2
It represents a logical fallacy to say that this is 1/2 of mass times velocity squared. When we do multiplication in a row like this, each value is multiplied together so mass isn't given only half value because velocity squared is also halved when we finish the calculation.
What I mean to say is, when using your intuition to guess at the importance of each variable in the formula, you should think of it as KE = (m x v^2)/2 so you don't mistakenly assign too little relevance to the impact of mass on the end result.
On the subject of momentum vs KE, both are simply tools that are often incorrectly used as general guidelines in killing power. In my earlier post I preferred momentum because it gives equal credence to both mass and velocity. Large caliber, poor/non-expanding bullets at low velocity are extremely lethal as proven all over Africa and right here in NA before the advent of smokeless powder. The KE figures on most of these cartridges are laughable compared faster, modern ones.
The most important thing for me is advocating that we cannot use either of these derived figures as a true measurement of killing power.
I'll give an obvious example of why this might be a bad idea. I'm picking on KE here only because I can't come up with a good example for momentum at the moment:
If we take a 22-250 Rem with a 50gr bullet launched at 3850fps we get 1645ft lbs of energy at the muzzle. This leaves 1200+ft lbs at 100 Yards, a figure I've often seen as "needed" for big mule deer.
I wish I could say I didn't have experience with what the 22-250 and such a light bullet isn't capable of on game that size, but I've had the "pleasure" of hearing a lot of stories (I work hunting retail) of lamenting hunters talking about their targets bounding off, leaving no blood trail and never being recovered. What went wrong? Not a very big hole and not very deep.
If we load up the same rifle with a 60gr Nosler Partition, the KE figures are almost exactly the same but we will see a much more favorable terminal result. I have locals that I have been unable to talk out of using their 22-250s that have at least stepped into the 55gr Fusions and 60gr Partitions and report good results from the change, even providing an exit wound in some cases. Maybe the hole is the same diameter as before, but now it's a lot deeper.
This shouldn't really tell an intelligent hunter anything, since we all know to choose cartridges and bullets that are suitable for the game we pursue based primarily on either personal experience or the experience of the hunting community around us. We can't rely on these formulas in a vacuum. I'm sure we all know that without me saying it.
New hunter's almost always ask, "What caliber do you recommend for deer/elk/moose/bear?". Experienced hunters usually suggest some bullets along with their pet calibers, do they not?
Canadian Bushman, the way you are using KE in my mind is perfectly correct. It is obvious you have weighed all the other factors you can (suitable cartridge size, suitable bullet construction) and are using it as a comparison between loads and/or calibers. After my whole speal, I have to admit I occasionally do the same. More often however, I am looking for a personal 2000fps breakpoint to determine my maximum range. I'm not experienced at long range hunting as of yet and this number coincides with where I am comfortable with accurate shot placement.