I am in the market for a computer that will allow me to train using a HRM. I currently have a cateye astrale 8 that works well but I am tired of having wires running throughout my bike. For this reason, I am looking for a computer that is both a cyclometer and a heart rate monitor and can calculate cadence for me. I had originally had my mind set on the Polar CS200CAD but have read some things about it getting funky readings. Apparently this was a problem with the first batch and Polar has since solved the issue but it still leads me to wonder if its worth the risk to drop that much money. That model costs around 150$ with cadence. I cannot find any other computers in the price range that offer anything similar. The next price level would be that of the S520 or 720i. The first runs 230 and the 720 would run around 260. The benefits to these seem to be their ability to do a ton of calculations, upload data, etc. The problem is that from what it looks like, I would have to maintain the use of my astrale 8 if I went with either the S520 or 720i. Am I correct with this assumption? The chart on Polar's wensite is a little confusing. The last option would be to make the jump to the Garmin Edge 305. This is obviously the best device but at 470$ for the edge with cadence and HR that is a hefty price tag. For that amount, I could spend a little more and get some sort of device that measurespower instead.

My second question is one regarding date uplink and its necessity. How necesarry is it to have this feature if I plan on training for races? I ride 6-7 days per week and try to get the most out of each week. I am trying to become a competitive cyclist. I didn't know if this was a necessity or even something that those of you who have the capability even use. One nice feature that I would like to have that only is offered on the nicer models like the 720i is the ability to read altitude and temperature.

Any advice is welcome. I want to spend as little as possible but like with anything in this sport, I accept the fact that you get what you pay for.
~Nick