I merely wondered if Hondas in general had inefficient rear window heaters. That's all.
This morning I left the ice on the back window and turned the rear screen heater on and it cleared fairly heavy ice in half a mile, Suitable for removal by the wiper. What I didn't realise was that on the first occasion it was heavy condensation inside the screen. (bear in mind I am having to concentrate on getting used to completely different tech from the K, so was actually looking where I was going. Not concentrating on the back window!)
So it clears ice satisfactorily, but won't get rid of heavy condensation. So no problem really.
I am finding, as mentioned in another thread that the car does seem to condense fairly easily in the mornings, which I assume is down to the odd weather we are having at the moment.