Have a read of this comprehensive discussion re winter tyres v summer tyres v all season tyres and the accompanying videos.
What I found very useful were the test results that show the increased stopping distances for winter tyres on dry roads.

"Another trade-off is in terms of marginally decreased grip on dry roads and at higher temperatures. According to www.tyres-online.co.uk/techinfo/winter.asp, even at 5 deg C, the dry braking distance from 62mph to rest is 41.5m with winter tyres compared to 39.5m with summer tyres (i.e about 5%). At higher temperatures the difference in braking distances on both wet and dry roads increases, to around 12% at 20 degrees C for dry and 3% on wet. Handling is compromised by around 11% too. Similar figures can be seen on http://global.hankooktire.com/Tech/h730_test_8.pdf. What Car? November 2011 give a slightly worse figure at 5.5 degrees C from 62mph of about 43m for winter tyres, about 16% greater than the 37m for summer tyres. Similar distances were measured by Evo Dec 2011 from 50mph. This is much smaller than the benefits on snow and ice and comparable with the improvement on wet roads (see “The Figures” above).

Have a look at http://spiritbodysoul.com/winter-tyres/ for the full report.

Tyre choice is a very subjective matter for us all regardless of how objective we approach the research on what's available.

I just thought the full comparison on the website may be of use to anyone in the throes of decision making re a new set of tyres for our UK winter.