Even One reaper still does OK, he's anti tank like a ravager, but in a different way. I do admit, from what I've heard having several is even better, however I've never seen this, all the DE armies with a reaper, only had 1. I've seen and read several battles with them, they did ok, and cost is ok, biggest obstacle is the price obviously, but it's not that expensive you know, compared to most forgeworlds. I've seen quite a lot of reapers because of this reason, he's very commonly seen, because he's effective and not that expensive.
The Tantalus is another thing. More expensive, again, biggest obstacle, but like the reaper, very useful in most armies. I do recommend to put him in the back or even in reserves, somehow people think it's a baneblade with huge firepower, but it isn't actually, it's a fraking transport for Khaine's sake. I do admit the firepower is useful late game if there's any infantry left. It's sad how people like to destroy it on turn one though ><, it's not such a big problem, since thye use ridiculous firepower for it usually, but it's anoying to see a cool model go down fast.
Both skimmers are seen quite a lot, very accepted in the dark Eldar community, I will admit i''ve rarely seen them in tournament enviroments, sometimes there's good reason, since not all tournaments accept forgeworlds... In normal games you see they quite a lot though, surprisingly a lot of people have them.
so In short, Tantalus gets shot down fast. People think it's big, it's dangerous, but it isn't actually lol.
The reaper, quite good, better in double/triple, but I think the main reason why he performs well, is because most people who face it, don't know it. Once they face it, they won't forget the experience though.
I was planning to buy some, but lost my job, ran out of cash, till I get a new job, i'll have to wait T T. I also want to test these babies myself, though I want them mostly because they look awesome. Unlike the FW raven though, they have an OK cost and they are certainly useful in battle. I still don't get my FW insists stubbornly on the FW Raven's DL to be twin linked, all the other flyers who have 2 DLs, they're not TLed ><.
The last stats could be ok if the cost wasn't over the top.