Potential new dark eldar player, should I take their advice

Talos and Cronos have always been counter intuitive for the reasons you mention, especially the Cronos. The Talos has always had the option of providing some long range fire support with its Splinter Cannon.

However, the new Coven Supplement gives them a nice couple of boosts in the form of two formations in particular. Corpsethief Claw is a single unit of 5 Taloi with Scout and Outflank to help them get further up the board. Dark Artisan is a single unit of a Cronos, Talos and Haemonculus; the Haemie can grab a WWP to get them deployed anywhere you want to apply pressure.

Add to that the now standard FNP, up to 3 models in a single unit, the FNP +1 the Cronos can provide, and they have gotten much more resilient in 7th edition.

Either they draw a lot of fire, keeping everything else safe, or they don't, and they will wreck your opponent's face. Often a little bit of both.

EDIT: note that using a formation won't take up a HS slot, so no tough choices there.