Is my Varia RTL500 finally dead?

Lol. I did. Nothing. Then I did again today and it seems to be alive again. After I bought the RCT715 for replacement.

Don't tell my wife.

Since you have the 2 models, the 715 is more sensitive in terms of detection than the 500?

I did a brief ride with both yesterday, and couldn't tell any difference in sensitivity. There was some weird behaviour, but probably due to 2 head units and 2 radars on the same bike. 

I was considering replacing my 500 with a 515 but.... Please give me feedback on your experience with your two devices.

After a group ride today, I found the 715 more sensitive to other cyclists behind me. Many more false alarms.

The enhancements from the 500 to 515 are Bluetooth, which only matters if you want to use the phone app instead of a head unit, peloton light mode (shrug) and auto-power on with head unit, which is nice, but is it really worth upgrading? Battery life might be better on a brand new unit also, but it is heavier and larger.

Having used the 500 for years and the RCT715 for three rides now, I would only upgrade if I wanted the camera (which I did). The 500 works very well, and the newer features on the 515 aren't really useful for me. 

DC Rainmaker has a nice summary here: www.dcrainmaker.com/.../garmin-rtl515-rvr315-cycling-radar-review.html

Thank you for your feedback, so only the intensity of the lamp which is significantly stronger on the 515 could be the reason for replacing my 500 which still works perfectly.

Yeah, if I didn't want the camera, I wouldn't upgrade.