The only downside is that they often require a lot of block mods so the overstroked parts dont hit anything.

For example, right now our shop is building up a lingenfelter 427 small block kit for a vette. Lets just say that I had to do a lot of machining to fit 427 cubes into a small block. Even the pan rails had to be notched to clear the rods

The problem with it now is that the rods are hitting the cam lobes. Since we really cant grind away on either we are hoping that either a reduced base circle or less radical cam will solve that problem.