This is just a brief update on the CS600X bike computer - I've been using this for about 6 months now, on a pretty frequent basis, but the majority of use has been on the turbo trainer.
On the whole I'm happy with the computer, as set up with speed and power/cadence sensors. The head unit itself seems to be robust with a good bike fitting to which the computer clicks firmly. I've not had to replace the battery in either the head unit or the HRM chest transmitter. The major concerns I have is with the power/cadence sensor. It seems to use up batteries a little faster than the other components: AAA alkaline cells, but not to an outrageous extent. The quality of the power data seems robust and consistent, though I cannot evaluate whether the absolute values are any way correct (I don't have another power measuring system to check it against).
The construction of the power/cadence unit is a little flimsy, with wires connecting the seat stay mounted battery pack and the rear mech jockey wheel sensor to the main power/cadence sensor being a little vulnerable to damage. I don't generally ride to power values, as the values themselves fluctuate quite a bit (I actually ride to a gear/cadence combination that I know from empirical tests correspond to particular power levels).
I've been using the Polar G3 GPS unit to relay speed/distance to the head unit. This means I can use the CS600X on all my bikes without having to buy speed sensors. I can just switch on the G3 and go (subject to resetting the head unit as described in an earlier article.
This is unfortunately a rather flaky bit of kit. It took me a while to figure out how to use it (the user manual is actually really crap), and even then it frequently refuses to find a satellite or otherwise malfunction. I think this is mainly related to power problems - either the contacts to the 1.5V cell aren't contacting, or the cell has run down. I find that the batteries don't last long - the manual says 10h of use, I'd suggest less, though perhaps the device drains cells gently when not in use. I'm concerned about getting through a large number of cells (the unit uses a single 1.5V AA cell), and I've explored using 1.2V rechargeable 2650mAh rechargeables. these work, but have a shorter battery life.
Overall, at the 6 month point I think the CS600X with the power option has been a useful piece of kit. The HRM bike computer functions are second to none, as one might expect from Polar. The power option is very good for the price, but a fiddly piece of kit that I would think twice about, particularly if I was planning to take the bike in and out of the car frequently 9as might be the case for a time trial bike). For my purposes - using it on a stationary bike mounted on a turbo trainer - it's been an excellent addition to my training armoury. I'm a little less enthusiastic about the GPS sensor. I think riders planning to use GPS based bike computers might be better advised to go for a Garmin (perhaps the new 500 model?).
To wrap up, just a brief comment on software. I don't particularly like the supplied Polar Protrainer software supplied with the unit (but have to use it to retrieve the gpx files). I download the hrm files to my preferred software (VidaOne Diet and Fitness for my general training diary) and Golden Cheetah for analysing the power data. To use the GPS data in Golden Cheetah, I convert it to tcx format at GPSies.com (unfortunately I cannot yet combine the hrm files with the tcx files), or to kml format at the same website to render as a Google map.