I have MWinters 700x35.
These are not fit and forget tyres. For a start they are incredibly difficult to fit, very stiff and heavy! Secondly, although they are rideable on normal roads theyare far from ideal if there is no snow or ice about.
The studs get ripped out on normal roads too. Schwalbe sent me a handful of spares after I contacted them. I struggled to put the replacements in until I discovered a nice little trick that worked perfectly everytime. Great tyres in the snow and ice - rubbish tyres for normal roads! I put them on when it snows, and take them off again afterwards - it's a pain but.....
As a last note, they work amazing well in the conditions they were designed for. I was quite surprised just how well they did work.
Not disagreeing with you but just to add a slightly different perspective:-
1. M Winters are easier to fit than M+ by way of comparison and it will depend on the rim you're trying to fit to as well...I've only used them on rims with a 19mm internal width...narrower, or deeper, rims may prove more problematic but I can fit them without a need for levers.
2. being rather anal I followed the bedding in process very carefully and have lost one stud in two Winters...though my nature led me to source spare studs just in case and they still languish uneeded in the garage
3. if you move from racy 700x23 tyres to M Winter then I'd imagine the difference would be shocking, much less so if you move from M+ 700x35s. Plus, if you ride on them for the Winter, boy do you feel fast in Spring.
4. I like the peace of mind, I pay no attention to weather forecasts etc unless I want to take out another bike, the allrounder is ready and waiting regardless of conditions. Though you can vary the tyre pressures to alter performance if desired.
5. totally agree on performance, twice now I've been certain I'm losing the bike sideways and they've gripped and held at an alarming angle...they aren't proof against anything but they certainly help