Darren
Snell tests are different to EC-2205, not better, not worse, just different. The main difference is the testing of repeated impact on one point. Therefore, common consensus says Snell is better suited to car racing lids (i.e. repeated hits on one point of helmet, as would happen when repeatedly hitting a roll cage). However, to achieve this the shell has to be much harder, and therefore absorbs less energy.
So, Snell shells tend to be harder than EC-2205 ones, and that helps, and hinders at the same time (i.e. better in some circumstances, worse in others). My advice...get a helmet that meets EC-2205
Jo