I flashed my RX 570's back in April 2017.
Claymore's miner has been working stable in version 11.4, 11.3 and any previous version just as well.
I think you guys complaining about crashes must have dodgy memory straps or are just overclocking too far. Just check the log, identify the GPU going down and dial back that OC.
good for you. there's however indeed some instability of the v 11.4 version.
Never before the application had crashed on me, and I'm talking hundreds gpus( with 11.4 already two occasions on different workers) also on some of the cards I had to reduce the mem clocks to get back to stable operations