Yes if you are going to wear your mx helmet. But you are protecting yourself from having the wrong gear. A nice light trials helmet would probably help the neck rather than hurt it. I can understand the concerns. (I injured my neck hopping on a damn bicycle and people wonder why I hate them!) I had problems for years. The problem riding trials is you have to look up! Just the weight was enough to make riding not fun. I would try the right helmet.
We are talking about different types of crashing. Fast uncontrolable crunch. To a slow arms out stop, and roll at the worst. And yes I`ve had my rear tire pass my front in a desert race while flat out and completely destroy a trials helmet in first gear!