Here are my main concerns with these guys:
1. They are expensive since you need both Shadowseer and Troope Master to make them work; one brings the Veil the other the PW.
2. They got no basic armor save so any vanilla unit with S4 can put the hurt on them since they are T3 and only have 1/3 chance at surviving basic attacks. So they are kind of like Mandrakes but worst since they have S3
3. Lastly no PWs, rending is great but only on a 6+
I am not saying they do not work by themselves or as IC escort. The Death dance namely FC and Hit&Run ability is awesome! But you really have to work at it and try hard and put alot of effort to make them work every game. So in essence you are working for them when they should be working for you.
i see your point, however, i really like the idea of pretty much always have a 2+ against shooting attacks. It really saves us a lot of points on our shadowfield saves. godforbid you roll a one, it was a cover save and not risk it shorting out on us. 30 points is a lot to waste on something that CAN short out like that. so thats why i like them as escorts in DE. i appreciate what youre saying about their lack of punch without putting a ton of effort into it. however, if you think about it, you can really get them across the board with hit and run.