Here is a report with a similar wireless (no cadence) unit
http://brommieskywalker.blogspot.com...reless-on.html
We have used the strada wireless for years (looks similar to the one you posted but no cadance and heart rate). Never used a cadence sensor. I presume it is optional if you don't want to install the second sensor. Our strada wireless unit is simple, reliable and has long battery life (it turns itself on and off automatically).
My GPS (Garmin 705) happened to have heart rate function and I used it few times for curiosity (on a second thought, I should use it more, especially on harder routes). It has a strap that you put around your chest, directly on the skin. The strap has a battery and transmitter that transmit the signal to the head unit. A little bit annoying but you get used to it.
I would search Amazon.com for reviews, for example here
http://amzn.com/B007IGSWIG . Also, if you buy from a place that accepts returns, you can see how it works for you with minimal risk.
BTW, there are other kinds of portable heart rate monitors, at different price points.
http://www.amazon.com/Heart-Monitors...8&node=3407971