I'd have to chime in that the F6F is slightly more sturdy than the P47. Though it seems to me that the F4F-4 is even tougher still. The only thing I can think of since I imagine modelling of how hard to kill a plane is has to be one of the most subjective parts of the game. You can't really messure it like you can speed, climb rate, etc. Both AC (F6F and P47) have a reputation as being very sturdy, well built, tough planes. The edge I think the F6F has at least in the minds of the folks at HTC (pure speculation) is that the Hellcat is a NAVY plane built to take the rigors of carrier operations whereas the p47, while tough, is not. I read an article where they dropped a F6F with gear down straight down (wheels first) off a 21' scafold and the landing gear held. I doubt any AAF planes could do that.
The P47 itself, all models seem about equally sturdy IMHO.