I wonder if this happened before or after the decision to make Conan.
Personally I really like the Stormbringer BRP system, it's nice to have an alternative to D20. As for rumours what about the one I've heard where Mongoose are developing their own RPG system to replace their use of D20?
The King said:
However both heroes fit well together as the Young Kingsdoms and the Hyborian World only consist of humans.
Well the Melniboné and the Myrrhyn are races that while close and humanoid are definitely not human. The BRP Stormbringer gave rules for them as PC races, no idea if the D20 version did or didn't.
As a personal opinion Elric also seems a bit more "high fantasy" than Conan. The Gods are real and meddle in the world, Conan seems to have a more Lovecraftian view where the existence of the Gods is questionable and they seem to have no real concern with the world.
I also think that Elric can be a touch LOTR at times with quests for mythical artefacts and the hero having the chance to really change the world and take on the Gods rather than just fighting the inevitable tide of barbarism as in Conan.