I know most people would be against using the Sload`s but I just love it, I love seeing the dot up almost all the time on enemies as I am spreading frost and swarm with my magden.
The reason I kept the set for so long as it gives some nice stats and the oblivion damage that always ignore resistance.
Comparing dps however I still have a feeling that 6k mana that Necropotence set gives would still be better for me more than the almost constant 6k oblivion damage from all the ticks from Sload`s.
I just have really no idea which set would boost my dps further and what would help me more, the higher base of magicka or a very often proccing high dot damage.