The MR Collector's Edition/eFX Precision Cast are nice helmets. They are made of ABS - which is closer to the original Hero helmets since they were also made in ABS.
This helmet is an idealized symmetrical Stunt. The details are nice and it is put well together. Regarding assembly in a way it seems to be closer to the unlicensed/fan made helmets, than to the fiberglass LE.
There are some issues with it though excepting the symmetry (which I will consider not to be a defect): the seam under the frown part which is too visible, the lenses are a bit too transparent, the foam inside is not the best and no stand included, nor plaque. Though you can get fan made stands and plaques, change the foam, and add new lenses and even fill in the seam.
But overall is a great helmet. I got my MR Ce years ago and I still have it, even if i have many more helmets that are way better and accurate than it.
If someone would like an accurate helmet I'd recommend the MR/eFX LE (still not 100% accurate) or the following ones:
AP = Authentic Props - because it's being pulled in ABS, the detail is not as sharp as the TE2
ATA = Affordable Trooper Armor - Is it made by SuperTrooper (Terrell from FISD/501st) from a CAP mold
CfO = Cast from Original - ROTJ helmets with special liners inside, but they are making other helmets, even non-Star Wars props
FX/GT= is a fan sculpt but not accurate at all. Many 501st members still wear this type of armor. The helmet is notorious for it's over-sized, bobble-head look.
Gino = very accurate helmet.
SDS = Shepperton Design Studios (Andrew Ainsworth - the guy who pulled the helmets back in 1976) - a lot of controversy here, but the helmets themselves are cool, and a bit more sturdier then the regular unlicensed lids.
SiMan/RS Props = the latest Stormtrooper helmet produced from a movie used prop (this is the ultimate Stormtrooper Stunt helmet and keeps ALL the details and bumps from the original ILM helmet)
TM = Trooper Master - a 100% fan sculpt but probably the most accurate armor in the world (for not having been recast from screen-used items).
TE/TE2 = Trooper Expert - TE has sold his molds and the new owner is going by the term TE2. Very accurate.