James
Look at Belfast 2005 thread on events not on teh NDAC site!!
Didnt do glenariff, on way back from torn calf, may do bangor relays with club otherwise it will be the Junior Jan 29 which is tough going.
I am 3hr mara standard and i use my hrm for tempo runs, and long runs where i am not looking at time and distance, just time in the legs.
dont use it much for shorter steady runs or my shorter reps/hills. The fact that i cant breath works on those days.
best to look into the ranges properly, many are just estimated guides and may well be 10% out, i used formula in Advanced Marathoning which takes into account resting HR and a work out for your Max HR
good luck