Broken: current master
Multiscatter GGX converges to a different result in Pathtracing vs branched Pathtracing.
It seems that MIS and "Sample all Lights" don't influence the final outcome but it is only related to Multiscatter GGX.
Here are the results, both rendered with 100000 samples.
Steps to reproduce:
Here is a .blend file:
Make one render with "Path Tracing" and one render with "Branched Path Tracing", then compare both.