i actually wondered what happened to maxwell while i was looking for alternatives to octane.
remember it being the first renderer that broke the realism boundaries. seems to be dead but on life support.
i was also using redshift and it was fantastic but some features are actually missing. volumetric gi being one of them:
for instance if you have emitting objects, they wont affect the fog whatsover. that feature has been a long time coming too. the feature request go back for years.
there is no perfect solution sadly, but depending what you need redshift may be just it. they certainly seem to have their sh!t together unlike otoy, hope the recent acquisition does not change that.