Death Strike is probably fine for guilds that are first getting into Nax. However, after a couple weeks in Nax10, your dps will start to make significant strides to increase their dps. However, tanks won't. Death Strike does very little damage and the threat gained from healing is almost negligable. This means that your dps will have to back off in order for you to hold aggro. I'm not that educated in Blood, but from what I do know, your rotation should include as many heart strikes as possible. This means picking up that pesky little talent that turns frost/unholy runes into death runes. Then your rotation is PS -> IT -> OB (or Death Strike, depending on spec) -> a whole bunch of heart strikes. Since your proposed spec doesn't include Obliterate not wiping out your diseases, you would want to use DS.