Sorry, I just saw your reply!
If you are mostly on piste I wouldn't go as wide as 100mm. Ski Magazine just came out with their gear guide, and I think looking through it would give you some ideas on whether you want an all mountain or an all mountain wide ski:
https://www.skimag.com/collection/2023-winter-gear-guide/ If you are on piste and not yet feeling too adventurous then you could even check out a few of the frontside skis - a couple of them listed are pretty versitile (I would stay away from the ones with integrated bindings).
I personally think if you are skiing a 100 waist ski you'll want to be skiing at least half the time off piste, and skiing powder at times.
When I learned to ski I started with very short and narrow skis, and it really suited me. I actually changed out skis every season and went wider and longer as I progressed. (You can sell your old skis on eBay.) But it wasn't until I really started valuing that time in powder and crud and the entire off piste experience that I embraced the 100 waist. And from what I've heard a 100 waist is only considered to be an everyday ski in the west.
A longer length should help with chatter at high speeds. But while it's hard to demo, if you can I think it's well worth the money!