Hi K,
No question that others have gone up the Mountaineers Route (and the Main Trail), and down the Main Trail, in trail runners. I expect many of them would have it no other way. I personally prefer a 3/4 high boot, that offers some ankle protection, and increased shock absorption.
I have worn a light boot by Treksta for several years. I wear the Evolution Mid GTX unless I expect to need crampons (then I wear the Alta GTX). The women's model of the Evolution Mid GTX can be see at:
https://www.trekstausa.com/node/29They call their design "nest fit", based on many 3D scans of feet, and it is a wide design. It looks a bit unusual, but I've worn out several pair (and keep a spare pair in the closet), and have never had a blister or problem of any sort. They require no break-in, and offer great traction (good for MR final 400). The last pair I purchased I bought on-line from a Canadian On-Line retailer, so you may be able to find them in Montreal. Check them out if you can.
John