Grim reaper broadhead flys like a field point, and is devastating on a deer, I have killed 3 this bow season and the farthest any of them ran was 50 yards.
This is what worked for me, a new crossbow owner/shooter as of this fall. At the recommendation of an employee at a local sportings goods store I tried the Grim Reaper crossbow heads. My CB is rated for 470 fps and the heads are supposed to be good for that speed, and are. He recommended using dental floss to tie the blades in place so they don't open in the target. That worked but had to be redone every shot. I had some VERY fine SS wire that works as well and lasts much better.
I found the accuracy to be equal to that of field points but they were 6" left at 50 yds. A minor scope adjustment fixed that. I had no problem keeping shots at 50 yds within a 1 1/2 inch circle.
A couple of weeks ago I had a 40 yd shot at a doe that hit right at my point of aim. The arrow went thru the ribs just behind the shoulders and exited, breaking one rib. The doe ran about 50 yds and died. Surprising to me, there was no blood on the arrow nor was there any to track, but plenty where she dropped.
One of the blades was bent but I was able to disassemble the broadhead, straighten the bent blade, and resharpen all 3 to hair shaving sharp. I have not used the broadhead again and prefer not to, but would if I needed to.
Grim Reaper sells replacement blades and springs so their mechanical broadheads can be rebuilt and that seems a reasonable option, although they are a bit dedious to disassemble and reassemble.