Darkie Lordy,
I believe what Gino says is accurate inasmuch as he has heard, seen, perceived, been told, directly experienced, etc. the Star Wars phenomenon. However it is more difficult to disprove something than it is to prove something. Anyone can prove the sky is blue. To disprove the sky is blue, you have to shoot down any notion of the possibility of the contrary.
In this case, GINO has to prove beyond a shadow of doubt that Stunt Armor cannot possibly exist. So the burden of proof is upon him. A mere word spoken with a quality of authority is insufficient. As always, PHOTOS are a big plus when establishing and backing up statements!
More to the topic, you should still expect reasonably accurate armor that fits your person but that helps you recreate the proportions of Vader. As I pointed out in a previous picture:
... even "Prowse-sized" armor is not truly Prowse-sized. If it's not obvious, the "Prowse-sized" armor appears to be larger than the screen-used armor!
So regarding neck flare.
In this case below, you WISH there was neck flare.
See the size of the armor neckline in relation to the size of the mask's head, let alone the mask's neck!
I trust the point is made! You should try to find something that is reasonably accurate looking but recreates Vaders physical proportions. You can't go wide, else he looks like a line-backer. You can't pad the shoulders, else he looks like he's shrugging and has no idea what or who Padme is.
Now Gino can probably more than easily explain the discrepancies of neck width and neck flare among the Vader vendors, but here is my take on it:
Now when you compare the neck of a 20th Century to an early sequence Don Post Deluxe (only 1,000 were made), there does appear to be a size difference. The Don Post does seem to flare out a wee bit more. The castings later in the Don Post Deluxe series showed the neck to flare out more.
Neck flare isn't bad so long as it covers the neckline. If it's too shot out, it's merely an aesthetic problem. The neck of the mask should lay nicely and neatly on the armor. This won't happen if (1) the armor's over-shoulder arch is misshapen, and/or (2) the neck of the facemask is misshapen.
If a casting hasn't fully cured and is removed from the mold, it is still going through chemical changes whereupon it can still warp and distort. If armor is set on the ground, depending on its uncured state, it might sag under its own weight.
I can't explain the Don Post Deluxe's right neck flare as a product of mold deterioration or degredation. Nobody's been able to give me a definitive answer. Molds will tear with repeated use, yes. But when you cast something, you typically have plaster reinforcement, so the mold will generally give you a reasonably undistorted shape. Perhaps JRX or VaderMonkey can cast some light on the issue.
And some variances could have been deliberate. Many try to duplicate the Tantive IV shots (the scene in Ep. IV where Vader first appears in the Rebel Blockade Runner). The problem with duplicating a screen look is if one does so without factoring in
perspective distortion. The closer the camera is to Vader, the larger the center of his face appears, and the smaller his domecap and flanges become. The neck unavoidably seems proportionately wider at certain angles.
Thus some Vendors have tweaked their castings in order to make them more accurate inasmuch as they perceive something as accurate. When you tweak one thing and you're oblivious to its interrelationships with other aspects of Vader's face, it throws off certain proportions. That's why certain facemasks look "on" and some look "off". And those well studied in the props can tell, "Oh, that's a Fyberdyne" versus a GINO, versus a Ghost Host, versus a Don Post or a 20th Century.
Unfortunately, what this means is that you have to shop more carefully. Armor from one vendor might not work with the mask of another vendor. And if you do a one-stop-shop with one single vendor, make sure they line up. I've seen one of the most acclaimed mask makers helmet placed against his own armor, and it was an ill fit. Even some vendors recast other's work, thereby perpetuating the problem.
What it comes down to is, what is your own size, and what do you need to do in order to approximate Vader's physical appearance?
In some cases, you might be able to modify the armor. However, as shown in above photos, certain armor that isn't accurate to begin with isn't necessarily helped through simple modifications.
I can take something like Aquamend and close up the neck gap. I'd have to eradicate the paint of that black center area, and then repaint it. I'd have a more snug fit without having to rely on foam padding to create a shrugging hunchbacked look. However, that center black area of the screen-used armor armor does not flare out nearly as wide as a lot of vendor armor, so while I can modify a vendor's neckline, it doesn't alter the width of their black center area.