Just read your review and reached similar conclusions about the Grip King pedals. The Grip Kings are good quality and smooth, but my feet would turn toward the outside because the pedals lacked support there, as you noted. After lots of experimentation I found VP-458 pedal model, double-cage pictured below, to have excellent support and grip (even when wet), but two problems. That pedal is not nearly as silky smooth as the Grip Kings (of course it is much less expensive), and it is no longer made. I'm now using the Nashbar land cruiser pedals and have found them also to provide excellent support, grip, and a smooth ride. If the MKS touring pedal does not offer the full support along the length of the shoe you seek, you should give the land cruiser, or similar bmx style pedal, a try.
Take a look at Shimano's MX-30 flat/bmx pedal.
Have had my pair 3-4 years, probably have 10000 km on them; they are smooth, solid feeling & not too heavy. They come with short and long pins, i use the short ones.
$$, they are not the cheapest pedal- but are probably the best long term value.
BMX pedals are awwwwwwwwwesome, in fact, my touring bike has the Nashbar landcruiser pedals already pictured here. Within the greatness that is BMX pedals, they're particularly great because they're toe-clippable, but I did have to cut a shim out of 1/2" thick HDPE to allow the toe clips to work with the pedal's overbite. Although really, with all the grip provided by both their size and by all the set screws in them, clips aren't at all necessary.
My first brief tour, I had single sided mtb-style rattraps, the kind that are intended to be used with clips. Rode 92 miles out to the ocean and my feet hated me from mile 40 all the way to the end. You need stiff soles to ride rat traps comfortably for teh long haul, and at that point, you might as well just go clipless. The Rivendell pedals look like a myopic academic study borne from some hair splitting conviction that touring cyclists have unique needs; if you want comfort and don't want the hassle of clipless, a good set of BMX pedals is where it's at. My needs aren't unique, they just straddle the product categories. Mountain bike frame, cyclocross handlebars, BMX pedals... I was totally satisfied with my Land Cruisers on twelve consecutive days of tour this summer.