Totally agree — I was recently approached by a guy who wanted me to integrate his feature (idea) into my product. Since I'm normally in the position of asking bigger companies to integrate my technology into theirs, it was eye-opening to see things from the other perspective. I found myself asking him the same questions that others ask me, and I could see how the answers I give might not be sufficiently convincing to my prospects.

Talking to other founders can be very enlightening, if a little depressing.