My favorite subject.
1. Snell test above the Snell line, think of a slightly larger version of a Hebrew skull cap and you're there. Reguardless of how good or accurate each test they perform is, the majority of of a full face lids surface area remains untested.
2. It's not that long ago that we were all dripping about helmets that fail the old British standard passing Ec22. The relative merit of Euro testing vs our older test is a moot point now, but an awful lot of riders weren't convinced that the new standard was an improvement.
3. Arai, Schuberth et al carry out extensive, scientific testing on their own and competitors kit, but they're not sharing the results or offering their design aims with the rest of us. The pathetic scoring of one of Schuberths top drawer helmets is taken by many to show some fatal flaw in the SHARP system, but the reality is that SHARP uncovered the unusual construction of the helmet. The method chosen (lots of foam inserts as opposed to a single moulding) allows for a superb fit, but the trade off is that the individual cells can be overwhelmed in a collision. Schuberth believed it a reasonable compromise right up until it became public knowlege that their helmet passes more force than cheaper alternatives, at which point they started questioning the validity of the whole SHARP process. Arai, similarly, don't feel that the side of a helmet warrants as much protection as the front, top or back. If they had a dotted line on the outside of the lid the size of 70's headphones with a warning that this area is protected by the users shoulder, not the helmet itself, would Arai fans be quite so happy to defend the firms decision?
4. Independant research shows an even distribution of helmet impacts in road accidents. It has also shown an area the size of a palm print, over the temples, to be particularly prone to damage in fatalities, often refered to as the "X spot". SHARP specifically test this area, and give it equal weighting to impacts front, rear and top. Next year ARAI claim all their UK helmets will pass at 4 stars or better, presumably by improving the protection over the X spot. If this is the specific reinforcement you're talking about Dime, I'm all for it! 
5. SHARP (as opposed to sound bite obsessive political slime) are at pains to point out that fit and comfort are vitally important in chosing a helmet and offer some advice on getting it right.
6. Lastly, there isn't a test in the world that looks at the long term durability of a lid. Luckily we live in the UK, so if your visor drops off, your lining compresses and your chin strap falls off, get trading standards involved. 
Hth.