This is one of those issues about which folks can respond with almost religious zeal, but FWIW my experience with long distance backpacking has all been in trail runners, in as rugged conditions as I think anyone would care to name.

At this point, the only times I'll consider using boots are (1) a straight-up and serious mountain climb, in which case I'd go directly to plastic boots and bypass any of the "in between" options, or (2) In some cases in early to middle winter boots can be good. But in fact I'm content in trail runners in snow generally too, sometimes using Neos overshoes. Because, indeed, once you have footwear that doesn't hurt you, you tend to want to push the envelope to using that footwear whereever you reasonably can.

All that said I've not been in the Dolomites. When my wife and I did some hut-to-hut hiking in the Alps in late 2010, we did find that whenever we got into a hut (where one always removes outdoor footwear), ours were the only trail runners every time. Europeans don't seem to have caught on to the concept that a person can go without boots and survive! :-)
To be fair, I found the east coast of the U.S. a bit more like that too, more boots on trail on the AT than on the PCT.

I do suggest that she try out a trip of decent length in trail runners, somewhere domestic, and not be experimenting with new footwear in Italy.