I know it, and it's the way to go after making backups. It's not that hard, but not trivial either. You have to install the old & new postgres versions alongside each other, shut the database down, etc. I've done it many times, it's not hard, but I wouldn't call it a "piece of cake". And it does require some downtime.
Anyway, my comment was simply responding to the parent's:
> Or you could just dump and load the database (maybe even pipe it from one to the next).