I have the 305 and I really like it. (You do have to get over the calculator watch look though.) I take it on my runs and today I wore it on my first bike ride in forever. I changed the watch to bike mode and it accurately kept track of my distance and time. However, I am not sure if I was supposed to buy another piece of equipment to place on my bike, but it seemed to work fine. The biggest thing that I like about the 305 is that it keeps working even with rain and sweat. My friend and I were running a few weeks ago when it started to rain. Her 405 stopped working (started back a bit later) while my 305 kept on going.
Not sure about the Polar since I don't have one, but I really like my 305 and I know you can buy a foot pod if you use it indoors.
10/09 - Komen 5K 30:52
11/09 - Maggie's Place 9K 59:18
11/09 - Iron Girl 10Miler 1:47:28
1/10 - PF Chang's Rock N Roll Half Marathon 2:29:18
11/2013 Women's Half Marathon in Scottsdale
| Pounds lost: 0.5