I think this to be a case of " extremes" . Krisken, your own bow is an extreme end of the spectrum example here.

Lets take a more realistic one in terms of speed, arrow weight and KE numbers. Take any of the 305-310 IBO rated bows on the market today and put an ultralight arrow setup on the bow...5 grains per pound. Just for argument' s sake lets say that results in a 325 grain arrow and an arrow speed of 280 fps (28 or 29 inch draw length and a fully loaded bowstring). That is " only" 56 ft. lbs of KE.

But, if you were to shoot a slightly heavier arrow...say a 100 grains more (425) then the arrow would slow down by roughly 20-25 fps (255-260 fps) and be producing anywhere from 61-64 ft lbs of KE. In all honesty I call that a substantial increase. Ofcourse, these figures vary greatly and the loss of KE/momentum in relation to an increase in arrow speed is not a bell shaped curve. There are " cut off" points at each end of the spectrum where too much arrow weight or not enough arrow weight is detrimental to the overall shooting characteristics of that particular bow and arrow combination.

The point being that though either of the setups mentioned will " do the job" provided shot placement is there, if shot placement is not perfect then a little more KE and momentum might allow you to still be more effective in putting the animal down. The key factor to all of this is to find what provides for the optimal setup for your situation.

Too light of an arrow normally does not produce enough KE, momentum or both..... can create a loud bow and can drastically increase the wear and tear on bow components. Plus the tradeoffs that a person normally has to deal with....low brace height, harsh draw cycle, etc.... can be more trouble than they are worth.

On the other hand, shooting too heavy of an arrow can result in a rainbow trajectory that makes yardage judging extremely critical. Take a bow shooting in the 225 fps range with a 600 grain arrow. That creates 67 ft. lbs of KE. Respectable in that category but then lets also look at trajectory...assuming an ICS carbon setup with 3, 4 inch plastic vanes and weight tubes installed.....and with the arrow parallel to the ground at launch.....

At 10 yards that is a 4 inch drop....at 20 yards it is a 15 inch drop....at 30 yards that is a 32 inch drop and at 40 yards it is a 58 inch drop.

Now, at the opposite end of the spectrum we take the arrow used in the first example....At 10 yards that is a 2 inch drop....at 20 yards it is a 9 inch drop....at 30 yards it is a 22 inch drop and at 40 yards it is a 41 inch drop.

That appears to be a significantly flatter trajectory especially when you get farther out into the 30 and 40 yard range. But, the arrow is probably going to be louder and carries at least 10 ft. lbs less KE.

As stated, these two examples are extreme ends of the spectrum. My point again being that I believe moderation to be the key. If we take the second arrow in the first example which weighs 425 grains and is traveling at 255-260 fps (64 ft. lbs of KE) and look at its trajectory.....

10 yards....3 inch drop....20 yards....11 inch drop.....30 yards...26 inch drop and at 40 yards a 47 inch drop ....

...then we can see that the bow still has a trajectory roughly comparable to the " speed setup" while still producing more KE/momentum and yet also offering a relative quiet, less critical setup.