@zoom123 said:
for complex scenes the draft engine could take many days to produce a result that the Production engine can do within a few hours? (i.e. you will practically never wait for the Draft engine to finish)
If you recall this thread you will see that for a reasonable scene, the difference between draft and production is incremental, not night and day. My impression was that it gets a slightly better result a little faster - maybe 10-20% (My subjective impression) If you give it a torture test scene, like one small daylit opening and complex emitters, sure, you may see a big difference, but I think it more has to do with how well you set up the lighting situation. It all depends on the kind of scene you are trying to render...