The thought of doing a major version upgrade in PostgreSQL (in this case, 9.4.5_2 to 9.5.3), always gives me the heebie-jeebies.
It could be that a couple years ago, when we finally got our 9.1 database at my startup out of the dark ages and went to 9.3, it wasn’t an easy one. We were running the PostGIS extension and we couldn’t use pg_upgrade with that, we had to do a full dump and reload. These days, though, I’m running a much simpler DB and upgrading my development machine’s version was super-easy.
At the end of the day, it’s all about just making a second data directory, porting the data over, then swapping directories. This link will show you how to do it in minutes. Don’t be skeered.