Personally, I think omega-3s are important to supplement and the others are not.
The (main) point of supplementing omega-3s is to reduce inflammation.
Inflammation, according to recent research, is increased by having too many omega-6 FAs proportionate to omega-3s which elevates the level of inflammatory eicosanoids (eicosanoids are a hormone). The typical diet of a US resident has too many omega-6 acids and not enough omega-3s.
So basically, I think the 3-6-9 supplements are bullshit and are too expensive.