I own and shoot both, the 160 grizley with 75 gn steel insert and the 130 single bevel No Mercy [ with 100 gn steel insert]
Both are great heads. No mercy is easier to get the correct angle on and keep sharp with Lansky Sharpener. I do like the wider cutting surface....
That being said.....If you use a good file and spend a bit of time attaining the prefered 25 deg angle on the edge... The grizley is a Very Good, tough broadhead.... Stays sharp and is easily touched up on the lansky or diamond lap after the initial filing.....With the thicker overall blade width I expect it works a bit better if heavy bone is encountered.
I took a pretty nice Muley Buck this year with a No Mercy and effectiveness was unbelievable.. Ribs in and out, lodged in the off shoulder, and about cut it off in the 3 bounds he was able to make after the hit. The first bound snapped the 5575 gold tip on entry side and stopped peneration.
This Buck was down and out in 10 seconds... as fast as, or faster than, many I have taken in my younger years with a 270 and showing as much or more wound dammage.
Make your choice, properly prepair the cut angle on either and rest assured.