For instance, I have thought about using very light 3D shafts for antelope hunting. I'm sure they would penetrate this light boned animal adequately, and the flatter trajectory could be a benefit on the long range shots sometimes encountered. However, archery elk season coincides with archery antelope; and I sure don't want to risk a light arrow on an angle shot at a 900 lb. bull elk. Now that I have a second bow, might think about setting up one of them for elk and one for antelope.
But even for elk hunting, the small diameter shafts - particularly the A/C Super Slims and the Axis FMJ - offer a medium weight arrow with serious penetration.
If you can afford the expense to maintain two different setups for two different species, and have the time to keep your shooting sharp with both of them at all times, that's fine. I think I'd just do one bow with the medium weight arrows you describe. Then I'd invest half the money it'd take to get that second bow and buy a good range finder.
Use the rangefinder on those longer shots at antelope. When you know the exact yardage, that bit of flatter trajectory won't be needed, and you'll have extra penetration potential in case something goes wrong and the arrow doesn't hit exactly where you intend.