In Denmark, a country of approximately 6 million people, there are three different regions running the public hospitals. Two of the three regions choose a custom system, whereas the third choose Epic.
The results apparently doesn’t favor Epic in that it costs 4-5 times as much [1] and has caused productivity loss 1.5 years after implementation [2] (links in danish)
Still don’t know if is a fair comparison though, since you probably pay the costs of adhering to process to start off with and only reap the benefits later. However the Epic implementation has also been bug riddled and I’ve also read that the procedures are designed for a litigation happy US and thus are not rational to apply here.