RE: Broadhead ?????
Hope you like your new bow. I been killing elk for 20 years with a Muzzy 130. I am not hitting 280ft/sec, only 260ft/sec. As you know the Muzzy 130 isn't COC, but that hasn't stopped it from blowing holes out the back side of an elk. The four blade construction make mighty fine blood trails. I have not kept up with the new braodheads, have had no reason to. But I will tell you that the Phantom was made right here in CO on the western slope. I have personally seen the broadhead kill elk, bear and sheep, but it wasn't produced by Muzzy back then. It still was a very good broadhead. With that being said, it may not fly well on your new set up. If you are shooting carbons with small fletchings control issues may come into play. You have not given lbs of draw or draw length. The Phantom is a good sized broadhead and the smaller broadheads seem tostabilize better at higher speeds.
For me COC isn't as important as FOC or total arrow weight. I am still shooting XX75s at almost 500grs, add that to 260ft/sec and with proper placement of shot = dead elk.
Good luck with your new bow and have fun.
Gselkhunter