True, the 370 gn arrow at 260 fps will have more slightly momentum. However, it will lose a greater percentage of it's speed, even at 20 yards, than the same arrow at 230 fps. You increased the speed BUT, wind resistance (drag) increases by the square of velocity.

The 260 fps arrow will still arrive at the target with more energy than the 230 fps arrow had at the bow. The ballistics table shows the 230 gn arrow starting out at 230 fps, 43 ft lbs of energy and arriving at 20 yards doing 219 fps and 39 ft lbs. The 260 fps arrow: 260 fps, 55 ft lbs and 248 fps with 51 ft lbs at 20 yards.

That's a loss of 11 fps and 4 ft lbs for the 230 fps arrow. 12 fps and 4 ft lbs for the 260 fps arrow. The differential in energy loss between the two arrows is too slight to be worth considering at 20 yards but it is measurable... if you want to run the calculator out to that many decimal places.

Contrast: I ran a 570 grain arrow at 185 fps to match the energy of the 370 gn arrow at 230 fps and checked the numbers at 40 yards. Starting at 185 fps with 43 ft lbs, it hits the 40 yard target at 175 fps and 39 ft lbs.

That arrow lost 10 fps and 4 ft lbs. It yields roughly the same numbers at 40 yards as the 370 gn arrow put up at 20 yards. That's why it's better to get your momentum from mass than from speed.

(By the way, that 570 gn arrow at 185 fps is almost exactly the arrow I use and speed I get from my recurve.)

Just for grins, the 40 yard numbers for the 370 gn arrow: 230 fps is down to 209 fps, from 43 ft lbs to 36. Loss of 21 fps and 7 ft lbs. 260 fps arrow is down to 236 fps, 55 ft lbs is down to 46. Loss of 24 fps and 9 ft lbs. The 260 still arrives at target with more KE than the 230 fps started out with but it still lost a higher percentage of it's speed and energy.