When I got fit at 3D Bike Fit, it was recommended I switch from Speedplay to Shimano pedals due to the more stable platform and greater resistance to pedal wear. I gave these a try, and indeed the feeling of connectedness was palpable. I expected to feel claustrophobic, accustomed to the freedom of Speedplay's rotational float over many years, but with Kevin Bailey's expert cleat placement, my foot was where it wanted to be and there was no need for it to be anywhere else. As long as I didn't think about the fact my foot was constrained, I was fine. And the pedals were light (248.0 grams on my scale), especially considered in combination with the cleat hardware, which is much lighter than a Speedplay cleat with adaptor plate (although I have no adaptor plate on my Bont Speedplay-drilled shoes).
The only time I noticed the constrained position was when coasting. I found that when I coasted, I liked to move my foot around a bit to stretch the muscles. This isn't as possible with Shimano's relatively fixed position. But really it wasn't a big deal. I rode the Devil Mountain Double on the Shimano pedals & cleats, and had no issues over the mountainous 200 mile route.
What turned me off on the pedals, however, was the single-sided aspect. I stopped once to indulge my navigational paranoia when the Garmin 500, as it is prone to do, warned me "off course" even though I was exactly on course. And then when I started again, I had trouble finding the correct side of the pedal. It wasn't that big a deal, a few seconds, maybe 5. But those 5 seconds meant I just missed a traffic light at the next intersection. All of a sudden 5 seconds lost became 30 seconds lost, and 30 seconds can make the difference in a placing, even on a route this long. And were I to use the pedals in a Low-Key Hillclimb, 5 seconds trying to find a pedal at the start is a similar time loss to 300-500 grams extra on the bike. If I had a choice of two pedals, one set 300-500 grams heavier, which would I pick? Which would you pick? 5 seconds is a big deal.
Of course it's possible with practice I'd learn to clip in as quickly with the Shimano pedals as I would with the Speedplays. But maybe not. And certainly I'd not be able to clip in quicker. Team Sky's policy is "marginal differences". You chip away at things which matter just a little, and in the end you end up with a net effect which matters a lot. This was one extra factor about which I didn't want to worry.
So after putting the pedals aside for awhile, I'm finally selling them. It seems a good time: road season is approaching, and people might be looking for new equipment now. The pedals certainly are nice, and I regret giving them up, but it's important they find a home where they'll be put to proper use.
As an aside, Garmin Vectors are based on the Look platform, and they also are single-sided. That's unfortunate, in my view, but I will give those a try as well, mostly because I'm so very interested in the L-R balance.