As someone else said, it's in production. Also, there are many, many forks of the EVM in production that run on proof of stake mechanics (Polygon, Binance Smart Chain, Skale, Qtum, xDai, etc). The main thing you have to worry about with move to ETH2 is contentious forks of the main chain, like if POW miners revolt and start a fork or a blip at the merge point that takes the chain offline for a bit. The ongoing ETH2 consensus and validation mechanic is live already. ETH2 also has client diversity, with 4 different implementations written in four different programming languages (Rust, Go, etc). There is some world class talent on the ETH core team. I have full faith in them and their testing regiment. But of course there is no such thing as risk-free.