They wont be around for long.
Anyway, Dark Eldar.
1 Warrior Box. Check. You definitely want one, at least to make Trueborn out of, or to have a Scoring unit in your backline.
20 Wyches. Double check. 2 units of Wyches to run forwards, one unit of Warriors to sit back. That's your 3 Troops, gold.
9 Reavers. Sad face.
5 Scourges. Double sad face. Mostly these guys get used as bit-fodder. Their sprue is excellent, and come with a bunch of weapons. Including Shardcarbines which are invaluable for making Trueborn.
1 Venom. Fine. Although you will need more.
1 Raider. Same problem as Venom. You need more than one if you have any at all.
1 Ravager. Again, if you have any, you need more than one. But, Ravagers are incredibly good and this wont mess you up in the slightest. Unlike the above where I would much rather have 2 Venoms or Raiders, rather than one of each.
Contrast with two regular-size Battleforces - which is cheaper.
20 Warriors. Not bad. 2 units of 10, one unit of 20. Base models for Trueborn, etc, etc.
20 Wyches. Solid.
6 Reavers. Not great. But at this level of play you take what you can get.
2 Raiders for your two squads of Wyches.
What you lost?
3 Reavers. Meh.
Scourges. Meh. Like I said, they're mostly used for bit-fodder, and for when min-maxing players have used up all their other slots. x5 Scourges, x2 Dark Lances = 140 Points. Bargain, really. But only after you've used your other slots because Ravagers have three Dark Lances for 105. And for 5 points extra you can get Razorwings which also have 2 Dark Lances and also lots of anti-horde power.
You traded a Venom for a second Raider. This is better. Especially considering you also have two squads of Wyches. Wyches need Raiders. This is not up for debate.
The Ravager. A loss, certainly. But two Battleforces is also cheaper than the Megaforce. Use the savings you made to start funds to buy one normally.
Keep in mind that the Space Marine one is basically the same; A lot of shiny toys but nothing particularly useful.