We had rain - freezing rain - sleet - and snow followed by temps in the single digits. I was able to thaw out and deice most the coupe, except the spoiler. The rear window defogger worked well. but added to the ice layer on the spoiler. I did not try to open the hatch to the boot.
When I hit the 50 MPH mark the spoiler could not deploy. I got an annoying constant alarm. I stopped and no way I was getting the spoiler de-iced. So as soon as I restarted, the alarm went off and kept going off till I reached my destination. Maybe it will thaw today, but temp are not forecasted to go over freezing until tomorrow.
I did do some freeway driving and did not notice any problems at 70 MPH. But I was reserved enough to not try to push it any faster.
The alarm does not stop, even when traveling less than 50. It restarts when you restart the car. There is no means to turn it off. Very annoying commute with the alarm.

 

The fixed JCW spoiler is a permanent solution. :-)

 

Try leaving the spoiler deployed when you park.

 

There has to be some way to defeat that alarm and/or the spoiler deploying. This isn't the first time it's frozen for a Coupe/Roadster.

 

What gemster said , keep it up when parked, and when restarting the mini, make sure the green led is lit.

 

I think there is a fuse passenger side footwell that you can pull to cut the spoiler. Not well advised on the switch as I have manually deployed but that is about all.

I love my rear spoiler and would rather have it than the permanent deployed one.