As a long time aspect cw eldar player, the first thing I thought I would cut from a combined list was the howling banshees. DE already have fast melee infantry, what could the banshees add to that.
But I'm having second thoughts, for a couple of reasons. First and biggest is the banshees mask. Denying overwatch that could weaken your wych cult units before they get into melee.
Second, wyches with shardnets solve the banshees biggest weakness, things falling back and exposing them.
I'd probably take them in supreme command with farseers or warlocks for psychic support. And maybe biker autarch for more banshee masks and joisting planes.