This was a topic of discussion with the other CM's while I was working on the design. After much discussion with a few of the senior CM's, I added the second life for the B5N2's. Primarily this is due to the fact that they have no forward guns. If we had the B6N's that were actually used in this battle it would be different, but we don't. The D3A1 does have forward guns and can maneuver very well and at least fight for it's self, something the B5N can't do. Also, in this design the D3A1's will be used in very small numbers and will have plenty of escorts.
After frame 1 I will review the results and discuss them with the other CM's. If we feel that the small number D3A1's are truly that vulnerable then a 2nd life will be added for frame 2.
My personal perspective is that FSO should always be a one life event, regardless of a particular aircraft's strengths or weakness (but that's just me). The most important point to focus on is the creation of a fun and balanced event for everyone. So, I will always be willing to change a design to achieve that goal, if it's needed.
Thanks,
Baumer