I did have the previous tread Michelin Energy's on my Xantia Activa. I had to use it through some of last winter, we didn't get a lot of snow but what we did I got around just fine with it.
Our oldest C5 is shod with Michelin Energy Savers on the front, its been through a few pairs now. That is very good in the snow, however it does have the smaller 15" wheels with 195 tyres, whcih cut through the snow better than the 16" 215s on my C5.
I dont switch that C5 to winter tyres as it performs ok with its standard tyres. I would say the previous Michelin Energys worked a little better than the newer Energy Savers, as they have some cross directional treads, rather than the straight groves in the newer type.
I do have a set of winter wheels and winter tyres for my C5 and our C5 estate, as they have the bigger 215 tyres and if I lost use of the car due to weather I would be scuppered. To be fair I have only ever got stuck in the snow once, this was with some very borderline (2mm) tread Michelin Primacy Pilots on my previous C5 VTR.
Before I got the winter tyres I went on a 2cv run last year with my C5 with Michelins with about 2.5-3mm of tread. The snow was deep, most of the run was on small country roads which were snow covered. I got there and back fine. It did come to a wheel spinning stop up one steep hill, so I reversed down and rally styled the car to the top
Pics from the run, what looks like water there is sheet ice, I could hardly manage to get out of the car

I really dont know what people do in the snow to no manage to drive in it. So long as the grip is maintained, good stopping distances are left and time is taken, its fine. So many people seem to apply so many more revs at the first hint of wheel spin, lose the grip and your just polishing the snow to ice. One morning last winter it took me more than 3 hours to do my commute due to weather and traffic. The roads were sheet ice, I must have passed more than 5 crashes, most of which were multiple car pile-ups. Too many people drive as if it’s a summers day, a good driving technique and you’ll still be getting around. It’s the other people I worry about, Id rather not be crashed into!
In short, unless we get an ice age happening over winter, you will be fine
