I originally bought a Polar Pacer, the older model with fewer features than the current model. I used it and a Timex 100 Lap Ironman Triathlon watch as well. It worked great for several years until the strap batteries died. I then replaced it with the bottom of the line CardioSport model, which was just as cheap as ordering a new strap. I continued to use the Pacer watch with the CardioSport strap. It was too bad the CardioSport strap didn't outlast the replaceable battery. Since the transmitter died, I ended up getting another Polar strap.
Since I always feel kind of goofy wearing the two wrist units, I decided to try a Timex Ironman Triathlon 50 Lap Fitness Monitor.
To start, although the strap was a much nicer pliable non-slip rubber than the first generation Polar strap I was using, I found the elastic strap when adjusted to it's maximum did not fit comfortably around my chest (I'm a bigger fellow, 6', 210#, and I wear the straps fairly loose). I had to unwind the loops in the strap and feed it backwards through the strap to get the length I needed. Then I found the Velcro loopback to fasten the strap on, to be a bit of a nuisance compared to the Polar strap as well.
Next I found the actual stopwatch/timer features of the Timex Fitness Monitor severely limited compared to the older Timex unit I usually used, for several reasons. You, cannot simultaneously display elapsed time in the current lap and total elapsed time for the event. You cannot toggle between the two when the stop watch is in use. As near as I can figure, you must choose from a set-up menu to show either elapsed time in the current lap OR for the event as a whole before you start the stop watch. Once you have selected, you are stuck with your choice until the stop watch has been stopped and reset to zero, at which time you can make the choice again. This seems to be true even when you are not using the heart rate monitor, and it only has a single countdown timer. Not to mention the fact I found the display very difficult to read.
And lastly (and this may have just been a bad unit), the watch was constantly loosing contact with the strap, or reporting bogus heart rates?
During my last run, I actually strapped my Polar unit on below the Timex unit, and it performed flawlessly, while the Timex unit continued to give erratic reading. Needless to say, the Timex unit was returned, and I'm back to 2 watch bands!
Summary: My Polar has worked flawlessly for 6 or 7 years now, other than replacing the strap for battery wear. The CardioSport unit didn't last a year, and the TImex unit was junk from day one. My next HRM will be another Polar. Of course, YMMV!