Video on new features in Reaper 6.37

Most interesting of which, to me, is the option of soloing the delta (difference between dry/wet) on every plugin in your project.

How useful/reliable is this feature? Obviously I've thought of this capability through use of reversing polarity, but practically I've never thought about it being too helpful/accurate in judging what's happening when using plugins. Anyone have any experience using this technique in helping to make mixing decisions?