@Daft Mugi, please test the latest source code SVN.
I fixed color banding issue and bumped default number of samples.
Of course, shadow maps are still as bad as they where, and you won't get less work for you GPU, but I hope most of artifacts in volumetrics themselves are gone now.
By the way, you can further reduce GPU load by setting "r_volumetricLowres 2", which would mean rendering volumetrics and quarter-resolution. You might get more blurry or messy look, but it should be noticeably cheaper.