I see we share a mindset on this one. I agree with you . . . and pretty much for the same reasons. Others here may wish to throw Colin Powell to the wolves (and, tacitly, cave in to the Dem attack machine), but I don't/won't for the very reasons that you stated.
And, I think the Rockefeller, Ellsworth, memogate/treasongate memo all arose in Dem Circles during Contra hearings. I look at what the "they write, what they are proposing. I look at the Plame/Wilson/Niger situation, and I see... something with players and events that trace back to the Contra hearings.
I cannot forget what I saw via CSPAN when former President Clinton tapped Colin Powell for "the job". I swear, if Mr. Powell could have tapped out Morse Code with his eyes, I wouldn't have missed that either. So, with gut, and with other data, I don't think Colin Powell is the leaker.