I am using the rsmb trial pack to render 2d mblur on an elephant I rendered out of maya. I am getting fairly good results in AFX but some of the profiles of overlapping objects still have some artifacts. I know this is a problem with post-mblur but i was hoping the rsmb plugin would improve on this. Is this an problem that is generally accepted or should I be trying to get better results? Am I missing something? I am rendering out as an rla (Wavefront) format.
You are not missing anything. In general we tell people to render different layers to add motion blur objects moving in opposite directions, which is hard to do when you have a character that is not able to be split into separate rendering passes.
Have you tried just using the version of RSMB that does tracking and doesn't use input motion vectors? That plugin will also produce artifacts, but they might be a bit less objectionable (or not, your mileage may vary :-) ).