The problem with Gorilla haven is that the eventual plan is to act as a 'bank' for animals that may be moved back out into the zoo population should their genes be required. An entirely reasonable process apart from the fact that, compared to the facilities there, many zoos have appalling accomodation for their gorillas. So, in welfare terms you have a potential situation of gorillas spending time at a first-class facility only to be exposed suddenly to high visitor volume, far inferior enclosures in order to breed from them.
Yes, there is some truth in that. But some of Gorilla Haven's residents will never re-enter the population. An example would be 'Joe' -one of their two existing gorillas. Also, very few Gorilla exhibits nowadays are appalling anymore. I imagine in reality, most of the future candidates for Gorilla Haven will be 'misfits' that can't be kept elsewhere- so I would think the 'bank' idea of holding gentically valuable males temporarily is rather less important than the 'permanent residency' part.
We could absolutely do with a European version of Gorilla Haven to house these problem adult males though.