I always bought hiking boots a half size down, thinking it prevented blisters, but my feet went numb on the Old Rag Mountain scramble last fall. A ranger at the trailhead saw me adjusting my laces and asked if I could wiggle my toes, which I couldn't. Do you go for a snug fit or leave room for your feet to swell?
Snug fit all the way. Loose boots cause your foot to slide, that's how you get blisters and lose control on rough ground. My toes just brush the front, never had a problem with swelling if the laces are done right. That ranger was probably just seeing one bad case.