I read some interesting comments on HFBoards in regards to Cowen's development from poster Heatley in Here, though.
He pointed out that Phaneuf and Weber, two guys whose offensive games I think we all dream Cowen one day replicates, both took two seasons in the WHL after being drafted before moving on. In Phaneuf's case, one could argue that the lock-out may have simply necessitated that, granted.
The crux of his argument was that there's no question that Cowen is (probably more than) ready for the NHL both physically and defensively, but in order for his offensive game to emerge he needs prime offensive minutes, something he's much more likely to get in Spokane than on Ottawa. If you bring him in too early, you may slow his offensive development since he'll be stuck behind a few defencemen offensively (it's the same reason I'm opposed to pairing him with Karlsson any time in the near future, since he'll be forced to defer to EK, as Hedman found he was doing at the WJC).
There's a reason there were whispers a while back about Cowen as a candidate for first over-all, and it's not just his defence. He's got tremendous speed and a strong shot, two foundational things to build an offensive game around. If he fully develops, a sort of (maybe slightly poor man's) hybrid between Chara and Weber isn't fully out of the question - that's why he was talked about as a first-overall kind of guy. What he needs to do is improve his passing game, and potentially even working on being a threat on the rush, since he's absolutely got the speed to do it.
I'm worried his injury set him back on his offensive development. I guess we'll have to see how he progresses this season, and I definitely see him in Ottawa next season for better or for worse.
Anyway, food for thought.