They don't seem bad from what I've heard.... but for the same price you could get a Blackwidow Ultimate from Razer. You CAN'T go wrong with those.
Yeah, the AX860 should be plenty for SLI-ing two 290x's. A little boost from the 760W to the 860W will make a difference later in the system's life.
Also.... I would totally go with the H110 or the H100i. They are both fantastic coolers.