Yeah...It looks pretty good on paper, but since it's so obscure, there doesn't seem to be much detailed info on it. Just another neglected dog, I guess...
Maybe our resident aerodynamics experts should get together on figuring it out
Seriously though they need to get that settled... Before it gets worse.
The only thing I can think of is there were problems with the engine output. (maybe overheating problems) or those figure are wrong on the weight of the a/c.
Where did you read that it was underpowered?
I could immagine other problems though. (ie bomb capacity and accuracy, even so it should have made a decent strafer and recon a/c)