Hi Olav,
Sorry, I don't check these messages very often so I didn't see your question until now.
I did some numbers way back and I found the average number of missions was about the same. The number of variables is too great to make a precise general statement, but I was pretty happy with the numbers I was getting. It certainly worked well for scenarios in the 6-8 turn range.
The benefits to my method are twofold. First, they reduce the chances of getting 0 or a lot of missions. Second, and more importantly, it keeps the OBA in the game so that the opponent doesn't get the knowledge that the OBA is gone for good.
Steve