In the interests of reaching more people, I posted the same message on the Whitney Portal Forum:

I have a permit for early September. I'm wondering if trail runners would work. I had to buy new hiking boots because my feet are wide at the front, and the Keen boots that I loved and wore for years are now narrower than they used to be, and started causing me problems. The only boots I could find that are wide enough are backpacking boots. They are comfortable, and solid, just heavy.

I recently bought some trail runners to try while hiking (Sportiva Wildcat 2). They have a fairly stiff sole, and were super comfy in the store (I haven't worn them yet in the real world).

To compare weights (with my orthotic insole): 1 of my new backpacking boots weighs 664 gr. 1 of my old Keen boots weighs 468 g, and 1 trail runner weighs in at 402 gr.

I have done a few hikes with the new heavy boots, and it was fine, but the longest hike was 8 miles, a far cry from going up the MR and down JMT.

All this to ask: Has anyone done the MR and/or JMT with trail runners? If yes, how was it? We have a day permit, so I won't be carrying a lot of weight.

Thanks, K