[Malawi]

Luxeon Rebels
http://www.luxeonstar.com/luxeon-rebel-stars-c-29.php

Cree XR-E R2
http://www.dealextreme.com/details.dx/sku.15943

Rebels will give a somewhat purple/pink tint, barely noticeable, whereas the Crees will give a somewhat green tint. It would be very difficult to find a "pure white" HP LEDs. Your choice really.

Very interesting ideed.

I guess that combining the rebels and CREEs should give pretty decent result.

I have som CREE spotlights that are not used for aquarium, but the light output and quality seems pretty good.