I'm using Corona Alpha6 for 3ds max (very,very old version corona, but it's free). I installed 1.7 RC5 and i made test for my interior scene which was rendered in Alpha6.
A) Alpha6 - 100 passes, 120 minutes, most shadows areas are noise clean (prepass included in render time).
after that i spent some time to get similar results in 1.7 RC5 (i made over 10 tests increasing passes, and i zoomed in every render test which i've done in 1.7 RC5, as long as i see no difference in noise areas. The reason is fact that Alpha has no NOISE parameter in output buffer to compare with RC5 renders).
Result after tests:
B) Corona 1.7 RC5 with denoising 0.5 - 40 passes + denoise took 14 mintues (with prepass).
For me is very simple calculation - 10 times faster with the same quality.
Resolution was 1920x1080. Typical interior scene with tables, chairs, office furnitures, artificial lights (ies) and small window for sky light.
What can i say - congratulations for Corona Team :) that's a reason to get Corona 1.7 licence and unistall Alpha6 Version:)
Greetings!