I guess you would first have to decide which features are of interest to you and pick the brand / model that has those features. I've only used Polar HRM's. The ones for runners because it measures distance with a footpod. Accurate, when calibrated properly. However, it's always calibrated at a certain pace (the one used when calibrating). You go faster or slower it's not as accurate. On my long run and medium run I use it to stay in my HR zone which is accurate. My two other runs are about speed (interval and tempo) so lap time is more important. But if I run faster then the speed it's been calibrated with, it's definitely not accurate. My Sat run is just for fun. The dogs (read: Spike), decides how fast or slow we go (read: how often he stops to sniff and dig and for how long). Neither time or speed are important then. I have the Polar rs800sd with the footpod. I could get a GPS with it as well. Suppose GPS is more accurate in measuring distance and speed if that's really important. This model also tells you about stride length, cadence (not much use when you run with dogs), running index, avg pace, and goes into detail for each lap (in my case a lap = 1K). I actually choose the Polar many years ago cause the Suunto was more expensive and the Garmin was not available here. I never changed brands cause I was happy with the info the Polar gave me.

The main reason I got a garmin 305 (besides price) was for the mapping features, which the 405 doesn't have.

Very interesting Blaine. So with the 305, I could go out and run some random route, keep track of the distance, and then come back home and link with my computer and map the random course I just ran? And the 405 won't do all of that? Do I understand that right? If so, my decision may have just been made for me.

On the TM I use the RS200sd. It's about 3 years old now and sofar I haven't had to change the watch battery but I assume soon. Footpod batteries I have to change about every 200K. Depending on how quickly I would turn off the footpod after using it. For outside I use the RS800sd. This one is almost a year old. Again no problems with the watch battery, but I have to change the footpod battery about every 350K (had to check my paper log to calculate that). But I think that would also depend on how fast you run? This particular footpod doesn't have a turn on/off feature. You can get a GPS with this model too. I'm juicing, juicing, juicing.

I have heard that the screen is smaller to view your data on the 405, which depending on what you want to see all at once makes it difficult to read while on the "run." IE, meaning I have my 305 set to show 4 things at a time, stop watch, distance, pace and current Heart Rate. Its nice to be able to quickly glance down to get those and be able to read them quickly. I would definitely want to see the screen size and readability on the 405 and compare. That's my 2 cents.

this is all very helpful. one other thing (i thought I read) to consider as I understand the 305 requires calibration on a track and the 405 doesn't? Aaron - awesome info!

I think the calibration is only for the footpod.

Correct. 305 by itself requires no calibration. FWIW, I would imagine that the larger display on the 305 would make it easier to work with on the run. I know they've designed the 405 to be an everyday sport watch, but most people already have that covered. Comes down to form factor and how much you like the idea of wireless syncing.

I'm not sure I would like a sports watch that needs recharging every day. And you're right, I have it covered anyway. So, how heavy is the 305?

The 405 says the following about battery life:

Battery life: 2 weeks in power save mode; 8 hours in training mode

compare to about 10hr typical for the 305. Weight: 405 is 60g (2.11oz) vs. 77g (2.72 oz) for the 305. SO the newer watch is 22% lighter. But I don't really notice the 305 on my wrist except when I'm looking at it. It's heavy and bulky as a watch, but fine for what it does. I'm not trying to bias you towards the 305, but if I were buying right now, I'd go with the 305 because •it's cheaper •I'm not compelled by the 405's wireless sync •no difference in features YMMV.