1 road bike (simple, light), 1 TT bike (could be more aero, could be lighter), 1 all-weather commuter and winter bike, 1 Monark 828E ergometer indoor bike
I found it to be a bit strange. It felt as if my feet were somehow disconnected, and I had difficulty getting full power in a sprint. But the worst issue was that I got massive toe overlap with that setup. After nearly taking a tumble once, I moved them back to the front as soon as I got home. I have no toe overlap on my roadie with cleats near the front.
1991 Rock 'n Road with two wheel sets, 1980 Univega Viva Sport with TA triple
I recommend no cleats, just regular shoes. One less thing to bring on the tour. Once, while pedaling through nasty wet weather in northern Australia, I tried pedaling in Teva sandals. It worked just fine.
It's been used by long-distance competitive (RAAM -- I think John Moreno might have come up with it) and randonnee cyclists for years. It is one very effective method of combatting Morton's neuroma, or hotfoot because it apparently imposes less pressure on the metatarsals in the ball of the foot, and therefore doesn't interfere with the nerves.
We are talking touring, so the idea of less efficiency for sprinting doesn't come into it. The issue of toe-overlap is a real one, and may end up deciding where the cleat finishes to provide a millimetre of clearance. On some bikes, even with cleats in the forward position, toe overlap remains a problem.
I have been sliding the cleats on all my shoes back as far as they will allow in the slots for years -- since I took up randonneuring and touring with clipless pedals, and after a bad episode on a tour in August 2002.
I am finding the Ultegra SPD cleats on my Shimano "go-fast" shoes don't go back far enough!
Touring cyclists are entirely free to use whatever they want... they don't have to conform with any particular fashion. Almost any kind of shoe with a stiffish sole will do with plain platform pedals, or with clips and straps (which is what I started with about 11 years ago).
Mid sole cleat positioning is fine as long as one makes a slight downward adjustment to his/her seat height because the effective leg extension is increased with the mid-sole cleat position. Without the adjustment knee problems can result. A number of pro riders have moved (pardon the pun) to mid sole cleats because it provides a few percentage points more power though sprinting capability is reduced. Standard clip-in bike shoes generally do not provide enough fore-aft adjustment to create a full mid-sole cleat position. One can buy cycling shoes that are specifically designed for a mid-sole cleat position though I'm not sure if these are available in the typical cycling shoes that a bike tourer selects.
It's funny, for a very long time I ran the cleats almost as far back as they'd go. All was well and comfy for thousands of miles with no fatigue or strain. Then one day it just felt wrong and uncomfortable. Moved the cleat up under the ball of the foot and all has been well since.
It results from the metatarsals -- the small bones behind the toes in the ball of the foot -- being compressed together and thereby compressing the nerves through that part of the foot.
The result is a sensation like overheating of the sole of the foot, especially in the ball area. Sometimes it feel like your sock is all scrunched up under the ball of the foot.
There are a number of causes, ranging from improper shoe fit (width, size, even the shape of the shoes where the ball of the foot sits) through to pedal cleat placement.
I don't recall anyone posting here or other forums, or involved in randonneuring, having knee problems resulting from fore-aft cleat issues; toe-in/toe-out issue, yes, but not the other. I could understand Achille tendon and calf strains with the cleat too far forward, however.