I don't mind it; it seems reasonable to me that a low-level player should get a greater reward for managing to kill a high-level enemy. Also, it seemed to work OK in DD. Level-scaling, on the other hand, is a complete no-no.
^This!
And also, I'd love to have D:OS without a fixed level cap. However, it should be designed so that the end level will fluctuate within like 2-4 levels, no more, and the final levels shouldn't be too different in power from the highest level to the penultimate ones.
