Well with the new Dark Eldar codex on the horizon it is hard to tell exactly how to defend and beat the DE's new incarnation.
If they don't change too much from how they are now this list will have a difficult time, without any dedicated anti-tank. Yes DE vehicles are as light as ours are, BUT they are Skimmers (which can easily be Obscured due to moving fast) and there usually are a lot of them. With only 4 units (yes I'm counting Wazz as his own unit) at best you could take down 4 Ravagers or Raiders on the first turn, and then find yourself assaulted soon after by other Raider squads and possibly by the survivors (as the bike's guns are 18" range, after escaping from the Raider that's 2 inches, + their move and fleet they have a chance to assault in retaliation).
Your biggest asset against DE for the time being is that they are the hardest enemy to play, but if played correctly they are the hardest enemy to beat. That's right I said it, and I mean it! With their ancient Dex from 3rd Edition they are STILL the hardest enemy to beat if they are being used by a player who knows what he's doing.
I have no shame in admitting that in the few games I've played against DE I haven't won. They've been close matches and a couple ties, but that's because the only 2 DE players I've ever played against really know their stuff, and I'm telling you that they don't fool around.
I think your best off with trimming down the Nobz mob, they don't all need PK's after all, the only models the DE have will really amazing saves are Incubi (which are currently limited to a 0-2 retinues for Lords), a Lord with a Shadowfield (which is 0-1 per army) and Talos (well I suppose DE jetbikes as well). After trimming down the Biker Nobz I'd look into a squad or two of Warbuggies, as they have cheap twin linked weapons with either Big Shootas or Rokkits. Rokkits would go the extra mile in Anti-Ravager and Anti-Talos ability to your army, but Big Shootas would have more shots, meaning you'd be more likely to take down Raiders and shoot up Warrior or Wych squads easier.
Tactics wise I believe a DE force will try to pick off your units one at a time, so don't spread them too much around the board, but don't keep them too close together either as a well placed Disintegrator blast will ruin your day (especially on the Nob Squad). Be very careful not to overextend your troops with this list as you only have 2 scoring units and you don't want either of them to get wiped out before claiming objectives. I know that the DE players I've played against would likely bring a dakka core against this army with multiple Disintegrator/2 Dark Lance Ravagers, a couple Raider squads, a WWP, and probably a large squad of Warriors in cover on an objective. Oh and it would likely be a Wych Coven which due to Wych Weapons is going to make CC difficult.
Best of luck against dem spikey heads