Although I don't have a cadence monitor it would be better if I got me one. Many bike improvement/training programs give you candence instructions. In my training it says that I should drive at least one training each week with a cadence of 100 (and that's really fast stuff) combined with a certain heart rate region. Look at lance what he was able to achieve with cycling at a high cadence.
I now have only a heartrate wristwatch mounted on my bike (a simple sigma). I tried to add a bike computer which measures speed but I hated it. I felt like keeping my current speed was more important then my heartrate, while it should be the other way around. And I was allways messing with the magnet to get it to measure something and when it did measure something it gave a ticking noise when climbing ... so after 2 weeks I removed the damned thing.
Maybe in time I will get the polar cs100 since it mounts so nicely on the steeringpen and I then got it all in one.