In my case, I always use the following:
Sampling
Min:-1
Max:2
Treshold
0.05 (x4)
Filtering
Type: Gaussian
X:3
Y:3
When I have to render more detailed stuff (like very small text on bottles stickers), I decrease the treshold to very small values, like between 0.01 and 0.025. This is the only way to avoid flickering.
Hope this helps
Salutations - Cheers
Bernard Lebel