Not it you want to compete with them in the search space (and subsequently search advertising space). It creates something of a channel conflict for them :-) Eventually to actually succeed at it you need your revenue not to be controlled by your competitor.

I dont really see why. You can always play Bing against Google and trying to compete in both markets when you haven't made a dent in the first one doesn't seem reasonable.

When we switched to their ads our revenue increased 10x which made us super profitable (we were primarily a federated engine like DDG though).