A large block has served me well for over three years. I shoot broadheads in on side and turn it to shoot field points and still has a fair amount of remaining life.
Broadheads will cut up the foam, and make a mess if you shoot it much. So, I bought a Yellowjacket broadhead target thinking it would work better, and save the block for field points. The YJ is made from heavy black foam. I think they laminate several layers together and cover it with the plastic cover (hence the name). However, it didn't take long before it started eating broadheads and inserts. It will pull inserts out of carbons unless you use epoxy to glue them in. Stuff like ferral tite or other glue is not strong enough. Also, forget about shooting field points into the Y.J. because it will wear-u-out pulling arrows. The retailer suggested selling it on c....list and buying another Block, but I am going to clean out the shafts and epoxy in the insert and give it another try. It is extremely difficult digging broadheads out of this target. Never had any problem with the Block.
After reading an article on building a target, I bought a few large heavy burlap sacks at the Feed and Garden store and plan to fill them with plastic (visqueen & plastic bags). I'll use two sacks for one bag then rope stitch the top.