Has anyone had much experience with them?

I need to get something so that I can have my phone on me whilst I ride at cable or out kiting (I'm on standby for work quite a lot throughout the week and need to be able to take calls).

I'm looking at the Lifeproof case & armband or the Amphibx armband.

Any one who's used either of these cases know if they're capable of taking the usual heavy cable crashes without being ripped off my arm?

One better than the other?

Any other products which would be more suitable?

Thanks