I have two Polars: one that I've had for ages with the usual wrist watch and a pretty basic display; and another one that I recently got with a display that mounts on my handlebars for cycling--the CS200. Both of them work pretty much as advertised, though the CS200 was a pain to set up. But once the setup was done, it's been working great.

The CS200 works as a bike computer as well as a heart rate monitor, which is why I chose it. I needed a new computer, so I thought it was best to combine the functions, though that might not appeal to everyone. I don't wear the chest strap all the time, like when I'm doing Saturday club rides--then, I'm just doing whatever I have to to keep up. But when I'm riding alone, the HRM keeps me focused--otherwise, I tend to just twiddle along, la-de-da, smell the roses, etc.

Those straps are eminently adjustable--they're meant to fit a very wide range of people, so you shouldn't have an issue with it fitting now but not later.