Won't really make much difference to me as I tend to do 90+ usually on motorways (when I can which isn't often), but if folk still insist on doing 50 when they join or leave it may cause more accidents, be nice if there was a minimum speed and that was enforced more.

Will 80 on M Ways come at the expense of 60 as national speed limit though? 50mph on B and C roads would kill off road rallying.