or do they develop play over time
They do develop play. It doesn’t really affect braking but if you rock bike back and forth with brake on there’s noticeable play in it, which is disconcerting.
Problem is DT’s adaptor just has lugs that fit through the 6 bolt holes and the whole thing sandwiches together with the disc and a lot of torque to hold it in place, but slightly thinner disc can mean it’s not solid.
Also, the ones that use external BB tool for the lockring, the tool snags on the lugs and wears them down.
There are alternates that actually use 6 bolts to attach the disc to the adaptor, which I might try.
Centrelock is a much better interface than six annoying torx bolts made of cheese that you manage to strips the head of.
Centrelock is a horrible abomination of a proprietary “standard” only DT and Shimano use. It forces you to use more expensive two part rotors (and there can be issues there with such rotors with failing rivets/bolts that join the parts). If it comes undone on a ride you need to carry a special tool with you!
6 bolts just work. If you lose one it doesn’t end a ride, and you can easily carry a spare and tool is standard.
Shouldn’t be stripping torx heads. You can get hex bolts but they will strip easy. Don’t torque stupid high, they don’t need much torque and just a little thread lock. Unlike Centrelock lockrings which require stupid high torque, which you are going to struggle to reach with a small tool you carry in a backpack without enough leverage.
Only reason I’ve got one is off-the-shelf DT M1900s that I’d got for HT and the retail models come with Centrelock. My other wheels are nicer DTs that I’ve had built up and always spec 350 hubs with 6 bolt.