I’ve been testing the Shimano PD-M8140 pedals on my 36er for the last few weeks. I think I’m going to keep them.
Previously I was using DMR Vaults, which I like from an ergonomic point of view, but they are frustrating in some ways. In particular the bearing tension is not adjustable, so if they develop play (which mine have) then there’s no way to get rid of it. The seals are also pretty poor, which has been a common complaint among many people for years.
Anyway, the PD-M8140:
Pros
They use cup and cone bearings so are fully adjustable. Like most (all?) of the current Shimano pedals the axle and bearing assembly unscrews from the pedal body in one piece, allowing easy service and bearing adjustment.
This also makes for easy regreasing without any need for bearing adjustment - remove the axle, wipe the inside of the body clean, fill it with fresh grease and screw the axle back in. Hydraulic pressure forces the new grease through the bearings and pushes the old grease out in one go.
They come in two sizes. I have the large, which I find very comfortable underfoot. They have a slight concave shape with no axle bulge.
The come with two lengths of pins, so you can tune the grip to your preference.
They take an 8mm Allen key, which is helpful for removing stubborn pedals.
Cons
They’re a bit heavy, at least in the large size. The small ones are comparable with other alloy pedals. I personally don’t think the weight is significant.
The grip is a bit less than the Vaults.
The multitool which I keep in my riding pack doesn’t have an 8mm Allen key on it.
The biggest con IMO - removing the axle from the pedal body requires a special tool. To be fair, it is the “standard Shimano pedal tool”, which is pretty easy to come by, but I wish it was a normal hex nut like on some other Shimano pedals. Realistically I’m only going to be needing this every year or so for servicing. Still, it’s annoying.