It's not all about wet driving. Winter tyres are of a compound that doesn't harden as much once temperatures drop below +7 Celsius. They should provide more grip & give you shorter stopping distances in cold conditions. Also they are so much better when we do get snow. I do agree that in south of England the benefits are less and usually you'll be fine on summer tyres if you're sensible.That would be my choice as well Micah. MPSS will be fine in wet conditions as long as you’re sensible.
2 sets is great but the extra cost might as well go to a new set of Same rubber once they’ve worn out!
Up here in Scotland winters are definitely worth it. If I want to travel south from Inverness there's really only one road (A9) & it does gain a lot of height and is snow prone. Usually closed 2-4 times each winter for anything from a few hours to a whole day. Alternative routes are significantly longer & also snow prone, but I would use winter tyres anyway for the superior grip in cold conditions.