I too will always use a map and compass for fell running - its probably be an age thing but I am more comfortable with that anyway. I generally will have recced the route anyway and in bad weather, will write any significant bearings on the back of my hand for quick reference. I do carry a GPS enabled phone in my bum bag and have on occasion (though not in races) used it to determine my current grid reference when in thick cloud but then referred back to the map and compass. I also have the OS Map app installed but generally only use this when walking in areas I'm unfamiliar with and can't be bothered to keep getting the map out.

I wonder if the use of GPS has been raised to the FRA committee. There is certainly a case that could be made that in certain circumstances, individuals could gain an advantage over rivals in a race.