[andrewingram]

As far as Apollo Client is concerned, I don't really know. I keep up-to-date with what's going on, but haven't really used it. Everything i've heard suggests there shouldn't be a problem, but Apollo is really good at marketing.

For Relay you're basically given no caching out of the box, but you can implement it by essentially hijacking the store's garbage collection to use an LRU cache instead of immediately evicting data when its dependents unmount. The developer experience for client-side schema extensions is similarly immature, but it is possible.

If you need all this functionality and aren't comfortable diving into the trenches, you'll have an easier time with Apollo (assuming everything works as advertised).