Hello Kuba.
I too have some issues with the Hasegawa kit but not quite the same as yours: I find the depiction of the raised lines on the control surfaces annoying for sharpening the trailing edges without damage to these areas, and the tailplanes are very thick, which is why I always use the Tamiya or other tailplanes on the Hasegawa kit (these Tamiya parts can use a very small touch more span added at the base).
I emphatically agree with you about the Hasegawa propeller, and I always use a modified Tamiya propeller which is the most accurate for narrow blades, with a bit of carving.
The Hasegawa cowl ring is accurate, but does not fit and "blend" as well to the Hasegawa cowl as the Tamiya cowl ring!
However I cannot disagree more with you about the Hasegawa canopy: The Hasegawa kit windshield's width of 5.1 mm is absolutely correct, and matches the width measured at 245 mm on a real relic.
I agree the real canopy's windshield looks much wider in most photos (looking as if the Eduard kit is accurate!), but that is only because of the extremely sloped angle: It is a visual illusion: Look at this photo from an unusual downward angle and you will see the Hasegawa kit is very correct (as the measured dimensions bear out), and how far off is the Eduard kit just below:
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I agree the too narrow Eduard tail is not really too bad once your resin has fixed the tailfin base, but the Eduard kit absolutely needs a better canopy that is narrower, unless a tarp is to be put over it...
To me the usefulness of this kit is strictly as part of a elaborate maintenance diorama, where it is in fact a better starting point than other kits if the goal is to have all the maintenance access panels open. The problematic cowl can then be left completely off for instance, but in no way can the late blown bubble canopy be used, as it is totally inaccurate in every way.
I would say with a narrower vacuform canopy, your corrected tailfin, and maybe a new cowl, there is indeed the basis here for something very interesting and useful with this kit, but closing all the panels on this kit, as most people do, makes absolutely no sense to me given the better Hasegawa release.
I wish you the best of luck with all your present and future corrections sets.
Gaston