Have you used DMR ? Have you found it better than a relational or a powercube?

Yes, I have used DMR. However, the performance here is not so great compared to a PowerCube. However, you don't have to worry about building cubes. I would suggest the creation of summary tables if you go the DMR route. There are limitations in the DMR that you don't find in PowerPlay. Again, it all depends on what you are trying to achieve. Today we typically build the cubes with TM1. But nothing is a flexible as PowerPlay. The question comes whether you need the drill down for Reports or Dashboards. If it is dashboards, you can create hierarchy there on the fly without DMR's or Cubes.