So.... After a few rides.
These have really really good stopping power.
They can take 2.3mm rotors, even though I'm running with standard 1.8mm.
I've seen these calipers specced with 2.3rotors and e-bike sensor equipped Moto style levers.

I'm actually much more impressed than I expected after the power ratio estimations.
Super light lever action, very easy to lock up, but really controllable.

ztto teams have quad 16mm pistons, so bigger, but the lever lets them down a bit.
Still good reports for them, but I'd still probably recommend these over the ztto teams.

Annoyingly 1 of the main underside lever pivot bolt has fallen out on my last ride, so 100% get locktite on the bolts if you get a set.
Only noticed as the reach adjustment started wandering inward.
Will be easy enough to find a substitute bolt tho.

So...
I've had a good look over them and can confirm some spec and impressions:
Caliper Pistons: 16mm/14mm pairs (I'd hoped they were 17/15)
Lever: 10mm piston, pivots 12mm apart, with lever grip 40-75mm from the master pivot and a nice curl at the tip.
Lever clamp: Compatible with Sram matchmaker clamp. (using sram clamp and bolt)
Finishing: Pretty good, anodising is a little fragile and can see where it's knocked about in the box a bit on a few of the sharper edges.
Initial impressions: Very good

1 lever came with one of the lever bolts half way undone, so had to tighten that up.
Took the chance to strip down the lever pivot assembly and get a good look at it. No loctite on any bolts, so will add some.
Can't comment on lever feel under hard pulls yet as not had it on a bar n disc yet, but initial impressions are good.
There is a slight forward back play from the tolerances of the threaded pivot section on the reach adjustment pin, but this could be due to the bearings.
Will look to get some 2rs bearings installed instead of the zz metal shielded ones.
Pistons look to be stainless, and fully hollow under the pad.
Need to reset the pistons back and check how freely they each move as they were uneven when received (had pads and spacer fitted)
I think the hoses aren't done up tight enough from factory, as I could twist the lever and holding the hose it would rotate in the lever.
Will take the lever off and review the barb/olive situation soon anyway as need to internally route the rear one.
pics: https://www.pinkbike.com/u/scar4me/album/Stuff/

Will update again when i've had a chance to fit, bed in ad actually get some usage.

I've got these brakes in 2 setups currently:
Onirii m4 - full original setup.
Onirii m4/PRO E4 calipers with Shimano bl-m6100 levers.
Running the same sintered pads in both, and same disc sizes.
Parts off Ali $70 a set n $25 per caliper. (Lookout for the deals!)

Power wise even the stock onirii's are good.
BUT once you add the Shimano servo wave they are up another level!
The stock levers have a bit of flex when really pulling hard, and the piston size means the top power is not as good as it could be.
Cue Shimano levers.... They have zero flex even when pulling hard, and smaller piston means higher top power.
But the servowave means that the lever pull isn't too far.
Result.... A much sharper feeling brake, with better power.
I do also still feel that the caliper has a bit of flex under extreme braking.

All in all, good brake on its a own, great brake with Shimano levers.

Scar

I've got a set of these sat in customs at the moment.
Will report back with detailed pictures n feedback once they arrive.

Scar