Ok, I carry and love the Grizzly heads and like Thom and a few others I will continue to shoot and use Grizzlies.
I contacted Biscuit Smith regarding the Magnus single bevel because both myself and a few of my customers had asked about a wider option for Single Bevel heads that were affordable. After some back and forth with Mr. Smith he agreed he would build them for Simply Traditional based on the 160 grain Magnus Classic. The additional width being the primary advantage.
As others have stated both are awesome heads, I can tell little difference in flight between the two. I have taken a lot of animals with Magnus Classics, and several animals with Grizzlies and both will perform well. There are a few dollars difference between the two brands but that is about it. The Magnus Single Bevels are $36 plus shipping and the Grizzlies can go as high $52 depending on weight.
I will be primarily shooting the Magnus this fall, hopefully there will be a few blood trails from this new single bevel design.