Can anyone help me with this decision? Which one to buy, the Forerunner 305 or the FR60. I am a female jogger who is training for my first marathon, though I regularly do 10-12 mile jogs. I've only ever used a Polar F6, mainly because I like that it tells me how many calories I've used. I now, however, want a watch that does everything that these two watches do. I get that the main difference is the GPS (305) versus the footpod (FR60). From reviews, both seem to measure accurate distance. Can anyone tell me if the Forerunner 305 accurately measures calorie use? ta.