All I have to say is, why? DEM doesn't even work right for cannons and if you put anything into weapons power systems, you shouldn't be getting hit by a drain. Marion is great for cruisers, my engineer with Beam Fire at Will loves DEM+Marion. I got 2 Marion and I can't believe they are only 1mil on the exchange, tempted to get some more.
Hi, my name is: Elim Garak, Former Cardassian Oppressor
LTS, here since...when did this game launch again?
Unfortunately I do feel they are pretty much best for a tac in an alpha strike, not as much an engineer because of how short the effect lasts.
That said, I did some testing and with three of them, you can fire a volleys of CRP 1 with 3 DHCs and 3 turrets, along with a DBB firing a BO 3, and lose maybe...15 weapons power from the whole thing all at once.
If an engineer does that and has Nadeon running, your weapons power will barely drop at all.