First, the rise in the cr<->CE exchange rate since right before the power surge weekend to now is closer to 600-700cr. Second, I highly doubt that the current exchange rate is much influenced by the two day power surge weekend. The rise is much more likely to be related to longer term trends and may well continue to rise. I doubt it will reach 7k, like it was before steam users came, since there are now useful for people who have CE to sell to get crowns. IMHO, there needs to be many more crown significant sinks added to the game.

Edit: D'oh! forgot my main point of replying: the power surge weekend was almost certainly worth it to OOO in terms of increased excitement, players returning, and good will generated by most players, and that is all that matters.