Almost ready to replace my second pair of trail runners, getting 400-500 miles per pair as a section hiker. Cost is an issue for them, but with poles, I find them to be much better than boots, most of the time.
Trail runners do not protect those bones that project from your ankles if your foot goes between two rocks. Had a scar on my left ankle for about a year from one incident. Hit my right ankle pretty hard in Mahoosuc Notch two weeks ago, but it is mostly healed now.
Since you have hiking experience, I think you should at least try trail runners. It is wonderful going mostly blister/foot-pain free. But in Northern NH/Southern Maine, trail runners are a questionable choice. I'm getting by, barely.