I didn't mean they are better then regular marines. The idea of having a whole bunch of them running around doesn't sit well with me, they use kill-teams of 5 to 10, if players can use then then you will have hundreds of them running around.

The Deathwatch are actually better in certain regards than their Astartes kin. The foremost factor is their experience and secondly, the wargear. Only Astartes who are the veteran of the veterans get to be in the Death Watch and though not entirely true, they technically serve a "tour" as they are "borrowed" by the Inquisition. When in the Inquisitions employ, they typically receive new armour and armaments if they choose not to keep their original Chapter armour. This is typically seen in why several of the members have identical armour as they receive the same from the Inquisition. You could see Death Watch squads in large amounts fighting against Tyranids because that is one of their specialties but they are really not much rarer than Sternguard or First Company formations.

It would be cook to have a special DeathWatch skin, as a Preorder or something, because they are just Elite Marines, the Grey Knights are Psykers and pretty special.

However, it would be also cool to be able to get a DeathWatch Shoulder as a Piece of Armour (like he served in the DW, but returned to his Chapter, these Marines are allowed to take the Shoulderpad with them)