I don't see why both cannot be kept.

I see the same thing on the DS side - iRay is awesome for photoreal renders, Octane (what little I've played with it) is even more awesome, but 3Delight is still hella useful in a lot of situations. More importantly, it is far more merciful on system resources.

Now here's a query for you - does Firefly have an external stand-alone render engine? What I mean is, can you export a scene to, say, .rib or suchlike, and let 'er rip?

Seems at least somewhat possible at first blush ...