Heard of them, but don't know anyone who owns one.

Blueprint is one I would avoid myself. I know a guy who bought a smallblock chevy crate engine and it was a disaster. It only lasted maybe a year and I think after it was rebuilt again only the block and crank were reusable and the rest was recycled metal. Many of the parts inside looked like they were previously used parts that were cleaned and thrown back in there. By the time he paid to have it all done right he could have bought two engines.