I would appreciate hearing your thoughts on this issue:

Should I go with
1) A Garmin GPS bike computer like the 500,
2) A Garmin GPS watch like the Forerunner 410 or 610,
3) An iPhone running Cyclemeter.

The background is, I'm a cyclist who hopes to start running as I start my fitness program this year. My cycling is daily commuting, spin classes during the winter, weekend rides when the weather's better, and a century or two each year. The running is to add some variety to my exercise, because cycling isn't breaking me through my weight plateau; I think my body's gotten too used to the bike. On the bike, I want to track speed, distance, course/elevation, time/splits, heartrate, and maybe cadence. I'd like to track heartrate on the spin bike too. I'm not sure what I want to track for the running - maybe nearest place to puke? - but I guess speed, distance, heartrate to start.

The 1) Garmin bike computer would be paired with a speed/cadence sensor and a HR strap.

The 2) Garmin watch would be similarly paired. I think these can be mounted on handlebars too.

The 3) iPhone/Cyclemeter would be paired with speed/cadence, HR strap, and maybe a remote handlebar display (thinking about the Wahoo RFLKT) so I can keep the phone in my jersey.

I have the phone and Cyclemeter app, everything else I'd need to buy.

What do you think the pros and cons of these choices are? Which would you choose?