Have Polar 800 with GPS (AUD 900). Was great for graphics, altitude, HR etc.
Now have Powertap SL which I ran in conjunction with the Polar.
However now run PTap only, with proprietary head unit, with a view to obtaining Garmin (500 800 something else?). I use Golden Cheetah, which is a vgood (and evolving) freeware, software program (cannot emphasise just how good with great modules).
My problem with Polar GPS was reception, battery life and accuracy of GPS mapping (was good in the open but drastically affected by tree cover etc). I enjoyed referring to data available (but not ideal). Also unfortunate that Polar does not offer Ant+.
To summarize, good choice IMHO. Good luck.
ps Golden Cheetah will accept both sets of data (from both Polar and Garmin) although I guess the 800 will cover all the functions of your Polar).
I have Garmin edge 705 and much better than anything i have had from polar only issue is its a bit bulky on the bars .
The speed is spot on with GPS . My wife uses it to check my driving from back seat. slow down going over the limit . It is spot on and shows the car speedo is out by 6kmh at 100.
The garmin training program is good also.
All I need now is for my wife to be able to pick me up on the computer and she will know when I am almost home and put the kettle on.
I also have the Garmin 705, after having the Garmin 305, Polar S625X, and Polar S510. While I liked the Polar S510, I hated, hated, hated the Polar S625X (POS!), and hated Polar's customer service even more.
The Garmin 800 is similar to the 705 but with touch screen capabilities, three screens of 10 data items each rather than two screens of 8 data items, temperature is one of the data items, and a better bike mount. Like the 705, the 800 can sync with other ANT+Sport devices such as most power meters, has great GPS and map functions, and is very accurate in most data fields. The 800 is supposedly more accurate for calorie counting. There are plenty of other features, such as virtual partner etc, to keep training rides interesting.
I have a Garmin 800. it is awesome. Make sure you get the Performance model if possible with the Cadence/speed sensor and the new soft HR monitor chest strap. The HR chestbelt works a dream. Most times don't even need to wet it. Cadence and speed sensor work well and is more accurate than using GPS. GPS is good though. Quick to load up and has some very useful automatic lap functions when racing crits.
All the data is useful, but you will want to upload it to something better than what Garmin offers. Perhaps training Peaks WKO+ or some other version out there. Garmin 800 will be even better if you have a Power Meter.
I put some maps on mine, but don't use them much. Could be good if trying out circuits that others have put online, or downloading a course, etc. BUt otherwise useless.
What I wish they had on there was Mp3 player with a mini speaker. Just to help pass the miles. All it does is beeps.
One warning. The glass on the Garmin 800 is very brittle and like mine can crack easy. it still works though. Don't bother getting dirt out of the sides. In fact go on ebay and invest in a high quality screen cover immediately and a silicon case. Otherwise it is the perfect bike computer. If you want to save money though, go for the Garmin 500. It probably has most of what 800 has in a smaller package and without the maps. But you have to sought of wait to you get home before looking at all the data. 800 has most of it on screen to access at anytime. And is totally customiseable. i'd buy it again for sure.