Boardman - yeah it's weird but whatever the reason for it, it's puzzling. I have noticed a bit more wear on the plastic adapter plates this time around more on left than right but having replaced the adapter plate with a new one on the left made no difference. Levelling out the cleat a bit may have helped but I definitely remember them being similarly flexed on both shoes in past and did not have the rocking problem.

I also gotta say that before the new set of pedals I cleaned (wiped with GT85 soaked paper tower or similar) the cleats and pedals pretty often - like not every ride, but maybe 1-2 a week, though they were not exactly dirty this time around.

The 105 pedals definitely feel a lot more solid in the way they hold your foot on both sides, however the right side did not feel bad to me with Speedplays.

Overall this is sort of disappointing, probably most so for not having a clear idea of the cause - user error or shoe compatibility (which are the same shoes as before and the left shoe has not been damaged in any crashes I had, only the right one funnily enough) or somehow bad pedals which does not look likely tbh.

Is there a SP rep around here somewhere? May try getting in touch with tech support see what they say.

And what does Speedplay have to say about this?

I personally have run Speedplay the last 1yr approx. I have Specialized Road Comp Expert shoes with the adapter plate on the bottom. I have only greased the spindles 2x maybe the past year, and I take the cleat assembly on the shoe apart every 4 months maybe and clean/regrease it well. I also never wear cleat protectors. I don't walk around in my cleats in the grocery store or out to dinner, and they are gouged up from stuff on the bottom somewhat though from rock/pavement/dirt at races and such.

My pedals don't rock and have worked the same since day 1.

So, either it is some tolerance issue with the manufacturer process, and just some variance from one pedal to the next, or something else is going seriously wrong. But there isn't much to a pedal, so that is why I asked, what does Speedplay have to say about this and what is their answer/solution to fix this?

A lot of top pros ride Speedplay, so I can't be led to believe they are problematic and can't handle world class cycling and different styles of riding/pedaling.

I loved them . I just seemed to wear the cleats out quite quick so went back to Keos.

IMO there is not anything "seriously wrong", but there are tolerances to all mechanical parts. And in my experience in manufacturing it only takes about 1-2 thousandths of an inch to make the difference between "too tight to fit" and "so loose it is rattling". Combine that with the fact that some people's pedaling styles really do cause the interface to wear faster.
I don't think speedplay will have a "fix", because it is not really a "problem". It is just the way the design is.
Going back to my own experience, I am sure the small amount of play I was feeling was never causing any loss of power or any other "issue" other than it annoyed me. If I were riding criteriums a lot I would go back to speedplay just for the quick entry and cornering clearance. If I needed float, I would also go back. Different designs have different features and drawbacks.