My concern with Monero is that optimized miner was always closed-source until a week in production. It happened each time the optimization takes place.
There was no closed source release of anything from the Monero project. It has all been released on github, when practical with accompanying Windows, Mac and Linux binaries. We can't control what everyone else does, but we have certainly encouraged optimized miner developers to share them, in one case offering a bounty (though it turned out not to be necessary as we independently developed comparable optimizations).
We're released two rounds of miner optimizations in open source, improving on the original bytecoin miner by approximately 10x (hardware dependent).