RE: Block 4x4
Yes and no.
They are an excellent target for shooting both broadheads and field points into - no question, howver; any time you shoot broadheads into any target it will decrease its life. What is going to determine the length of time you'll be able to use it is how frequently you shoot broadheads into it.
We put well over 500 shots into my Block 4x4 last weekend (four of us shooting a mixture of broadheads and field points) and it is definitely showing signs of abuse. We're heading out again tomorrow and will probably put another 300+ (two of us) into it. I don't expect it to hold up past this hunting season.
The ability to roate the target and shoot at four different sides is definitely a plus. Its an excellent target if you're looking for a multi-purpose target.