Previous Boston accident
Back in the '70's, a Britannia at max take weight tried to depart from Logan to the UK.
It was snowing and the a/c had been de-iced but between completion and take off, the runway was changed so by the time they were airborne, the horizontal surfaces were covered in snow again. The poor old Brit was never designed to cope with severe icing plus they then encountered wind shear. Only the Flight Enginneer, miraculously, survived the accident when they flew into rising ground. I lost many good friends that night.
Amongst other things I now sell aircraft de-icing equipment to airlines, and airports. I have also been trained on how to de-ice. Having also flight operating experience it's a no brainer that you should start with wings/tailplane clean. It doesn't matter if you have snow, snow/ ice or ice only on them, get rid of it. That way, assuming nothing else goes wrong, one take off will be followed by one landing and nobody killed.
However, the forgoing debate on de-ice or not to de-ice is stimulating. I only wish that everyone would grasp the risk if you dont. As I tell those I meet on the ground ''You only get one chance normally to get it right, if you dont de-ice or you do it badly, you will watch the accident happen''