The documents state what the situation is "in general".
However, you aren't running PostgreSQL "in general", you are running it on specific hardware with a specific pattern of use.
So - if you care a lot, then you'll want to test it yourself. A GiST index will always require re-checking its condition. However if the queries you run end up doing further checks anyway, a GIN index might not win there. Also there are all the usual issues around cache usage etc.
For my usage, on smaller databases with moderate update rates, I've been happy enough with GiST. I've seen a 50% improvement in speed with GIN (across a whole query), but it's not been worth the slower indexing. If I was building a huge archive server it might be different.