Biggest issue with the Eduard Hellcat for me is the fuselage tapering from the firewall as depicted (wrongly) in most drawings: Correct drawings and other issues are mentionned here:
http://www.geocities.jp/yoyuso/f6f/f6fe-1.html It should be noted Eduard's own 1/72 Hellcat has apparently fixed the tapering-from-firewall fuselage issue: Huge kudos for Eduard for recognizing this problem...
Ignoring this (fairly hard to see) issue, and the Eduard's slightly too long gear legs and skinny tires (both easily fixed), the biggest remaining problem is that the propeller is poor (undersized and simplified spinner among other things) and I find all separate blade resin replacement props to be useless due to the impossibility of securing a perfect alignment, especially on 3 blade props where you can't even use the opposite blade for alignment or the easier to judge square angles.
I think resin manufacturers should have realized by now a one-piece prop is the only way to go...
I have yet to see in person a separate blade prop of any kind that looked anywhere near as well-aligned as a one-piece prop, even on four bladers, and this extends to the majority of on-line builds, regardless of subject (but for some reason more noticeable on P-51s and P-38s)...
For the Eduard Hellcat kit I would recommend sacrificing a one-piece Tamiya F4U-1d Corsair's prop which is correct for the Hellcat and far more accurate in every way.
Gaston