I've got some birthday money and the pesky Achilles pain that had me couch-bound and snappy is abating, and I'm wondering about a garmin. Currently using runkeeper on my phone, which is fine except I don't always want to carry a phone and as the long-term plan is to do long distance trail runs, I'm concerned battery life might become a problem as I improve as well. Dunno. Anybody want to convince me I need one? Or that I don't?