Im preparing for a ultra run which i expect to take me around 15hrs. however im pretty sure that how it stands, my watch will not be able to last this event with GPS mode and HR. Currently i use GPS + Gallileo and I can get, around 10hrs. Does it make a big difference if i use GPS only? I had tried UltraTrac and i thought it was quite rubbish so i would like to avoid it if possible
