It is not difficult to have a dophinstrikerless mainbeam. Just order an alu beam with a much ticker wallthickenss. Actually the first Stealths were build this way and so you can contact John Pierce and ask what he used.

Downsides are indeed added weight and the fact that the mainbeam will never be as stiff as the beam with a dolphinstriker. The latter will impact negatively on your pointing ability especially with a modern squaretop rig as these require quite some leech tension upwind. These are actually the reason, I believe, that the newer stealths were quickle all fitted with dolpinstrikers.

Wouter