I have both a Varia UT800 (2.40) and RTL515, they both connect just fine to my Edge 1040.
I came from an Edge 530, and the introduction of the Light widget is a really nice touch, its great to be able to override the light mode and some of the automatic features.
I've noticed an issue, however with the Automatic UT800 Headlight Beam Adjustment, which worked just fine on my Edge 530.
Picture this, you're riding down a pitch black country lane and the automatic algorithm decides to turn the lght off, then maybe flicker it on and off. I've not found any pattern in its behaviour around speed or gradient of road, typically i've been on fairly flat roads. Its completely dangerous, and i've had to resort to manually overriding the Headlight Beam Adjustment (via the light widget) to be either High or Low. The light then behaves as expected.
Admittadly i've not been out in the dark for around a month now, so maybe this has been fixed in recent firmware.
Anyone else had this?
Cheers