My Mac mini has 16 GB of ram and the difference between 8 and 16 gigs is remarkable and welcome.
But it is important to stress that this will not be experienced by all.
If you only go on the internet with the machine you can feed it as much memory as you like, it'll make no difference.
For something like After Effects or other complicated stuff that uses a ton of resources, yes. Otherwise no (8Gb is bare minimum these days anyway)