No muss, no fuss, here's the list:
White Scars - CAD
TH/SS Bike Captain
Khan w/ bike
2x 3 man bike squads w/ 2x melta, combi melta
3 man bike squad w/ 2x plasma, plasma pistol
3 man bike squad w/ 2x flamer, combi-flamer
2x 3 man bike squad w/ 2x grav, grav pistol
Dark Angels - Ravenwing Strike Force
Interrogator on bike
ML2 Libby on Bike
Sammy on Corvex
2x 3 man Black Knights
Crusader w/ battle cannon and gatling cannon
So, let's start with the absurdly low model count. 2500 and we have 30 guys on bikes. Not even, actually. Havoc just about tabled that at 1850. So, when the other guy's 1850 tables the meanest part of your 2500, there's an issue, and a sizable one at that. We've got a lot of 'fat' tied up in special weapons that won't get to shoot (because they'll be super dead), and, you know, pistols and plasma, never mind the flamers.
Then there comes the obvious question: Why are we investing in White Scars when there's already Dark Angels showing up to the party? Especially when they're part of the Strike Force, and we're only bringing Khan, never mind missing the opportunity to include the Shield Eternal. Why oh why are we taking White Scars?! For less than the price of Khan (never mind our Captain), we can retain all our rules and more, courtesy of built in scout and grim resolve. Oh, and let's not forget, the rerolling 4+ cover is better than the 3+ standalone. Add to that the ability to take even more black knights if we so choose (instead of those plasma bikes, especially since these can include an apothecary), and there's almost no reason to play WS. We're not using their warlord traits or tactical objectives, not bringing TSE, don't have a chapter master or ironclad(s), so, why go blue?
Once we ditch the blue and white, we could just copy and paste the bikes into the list, but I'm not so sure that's the right call. As stated, we've got some real wargear inadequacies we could easily shore up. Let's start by reorganizing our bikers, and start with a configuration of 2 5 man Black Knights squads, plus 3 5 man grav bike teams. Already, we've upped our 'effective' weapons count in my opinion, because each bike squad now has two ablative wounds it can suffer before dropping a special weapon. I'd suggest keeping the Sergeants bare for now, and coming back to them later. We can give them meltabombs, and a grav is going to be more costly (relatively) than just bringing another biker with a regular grav gun, especially if we were previously rocking pistols.
We've cut everything but Sammy, and find ourselves at just over 1050 points. Even if we take the Knight and Stormwing as-is, we're only at about 2k, meaning we still have ~500 points to play with, and all it cost us was 4 HQs worth of
So, in the end, our final list is far more condensed (and fits into two source events!):
Ravenwing Strike Force
Sammy on Corvex
5 man Ravenwing Command w/ apothecary, and champion
5x 5 man Bike squad w/ 2x grav gun
3x Crusader w/ battle cannon and gatling cannon
Now, that's written with consideration for Gravemind's point that he really misses the long range shooting options in his White Scars army, but if I were going in blind, I would have opted for a Gallant Lance, and used the ~300 points I saved to toss in some meltabombs, and a few multi-melta attack bike squadrons. In either case, the list feels lean, mean, and, above all, fast. Just in case Dark Eldar players wanted to escape.