Phase Pistol, I agree. I've been staring at ILM X fuselages for years, and with the exception of the Red 2 nose up-turn, they look practically the same to me, minor diffs being caused only by the stuck-on nosepieces. That is, they all have a commonality not shared by the EFX, CC, or Salzo. As far as I'm concerned, the differences that exist between ILM fuselages (except Red2) are negligible and can be ignored - even pyros. What I mean is, if you succeed in capturing one ILM X fuselage then you're far closer to all ILM X than you are to any replica yet made. Such a standard would count as perfection in my book.
AT-Luvah, as to the differences between, say the V3 and ILM, well, I've gone on about it in my thread about the V3 - perhaps to the irritation of some, I don't know... but since you ask...
The errors are small but visible. Some of us feel the front of the canopy on the V3 is too wide, giving the ship a slightly stubby feel when compared to all photos, old and new, of all ILM 1/24 Xs. For me, this was instantly visible as the first photos of builds came through. The canopy top is somewhat too wide and too short, and in the top view the angle where the starboard canopy strut meets the fuselage is turned inside out. However, the kit was still accurate enough to warrant my blowing 300$ on it! I'd give it 9 out of 10. And from most angles, it's a dream to behold.
But I can see the differences between it and every ILM X photo I possess. I don't WANT to find differences, but they just jump out at me. I think the entire fuselage slopes a little abruptly. Evidence of this is that the V3 has a smaller gap between the red stripe and the top of the fuselage at the point where the stripe meets the nosecone. The cockpit seems to be placed too far forward, which seems to bulk out the fuselage, giving a squatter look in the plan view than to what we see in the plan view of Red 3. These are all solid deviations from every ILM X - pyros included, seems to me. An ILM X fuse feels sleeker, narrower. But, just how much one cares about these errors is entirely subjective, I guess. Still, if we're talking perfection - the kind of perfection we're seeing in the Neisen TIE or Monsieur Tox's work - then these errors are the final issues which need sorting out.
The reason I think the X fuselage is one of the toughest nuts to crack is because it's not based on simple geometrical forms like the TIE, the Y body or the Star Destroyer, which are all worked up from spheres, cuboids, cylinders, trapezoids etc. One of the biggest headaches has got to be the way the forward fuselage edges blend from a hard edge to a soft edge. To execute that while keeping the edge correct-looking from all angles - without working from cross-section plans of an original, must be a nightmare. In the whole fuselage it's like there are very few constants to get a hold of. So many tapers, and across long and very difficult to determine distances. About the only thing that you can grab hold of firmly is the horizontal line between the upper and lower body halves. And, since the cockpit isn't just stuck onto the fuselage but entirely integrated into it, the slightest error in any part of the forward upper fuse is going to show up in the canopy. Plus, the original was a hand-sculpt so it's like trying to copy someone's handwriting... has to be said, Moe made a heroic go of a very difficult task.
I don't think anyone would buy my Hero kit. The panel lines were done individually on the Hero models and I know people won't want to do that kind of thing. I know I'm not looking forward to it. Still, my original point remains valid. No one would want to do this much work themselves, or just a few at the very least. 
