Earlier this year I asked a Brawn engineer whether he thought the team would have been as competitive if its cars were still using Honda engines instead of Mercedes.Interesting reading.
The response came back firmly in the negative, and various disparaging remarks were made about the quality of Honda’s engines and their inability to remove the skin from rice pudding.
My view has been that the Honda engine wasn't impressive, but still somehow wasn't impressively bad enough to justify being re-balanced as the Renault engine was. The Mercedes engine is clearly the powerplant to have, given the success of Brawn, McLaren, and even more amazingly, Force India.
Based on that I conclude that while the double-diffuser would give the Honda an edge at the beginning of the year, the team would be quickly caught as the rest of the pack developed similar pieces, and we would probably have been left with a Red Bull championship in 2009.