There are so many great broadheads out there it can be hard to choose.

I have never used a Grizzly head, but not because I have never heard good things about them. Their reputation says it all.

Personally, I use Zwickey`s most of the time.
For me, a big fat Delta is hard to beat.

Good news is, you can`t go wrong with either.

I didn't read all the post here but you have picked 2 of the best heads ever, ether one will do a great job.

The only thing I would say is the 2 blade will always go deeper than a 4 blade, it's just physics.

I used 4-blade Zwickeys (both Eskimos and Deltas) for several years. They're an excellent choice. If I were inclined to go back to 4-blade heads, I'd use either again without hesitation.