I think that would be worth it, yeah. Of course if you are hosting it on your home network there will be some added security concerns (and that might make it better to only allow signups to friends/friends of friends/etc). The way I see it is that some instances are going to host the largest communities, and therefore those instances are going to need to handle all of the incoming/outgoing updates to posts in those communities. Right now they can’t do that reliably and push updates out to all of their users’ devices.
So in the long run I think having small/medium instances (say a couple hundred, not tens of thousands of users) will be the way to grow. These smaller communities can push updates to their smaller user count reliably, and then have more resources to handle federated content coming in and going out. I think scaling for the incoming/outgoing federation requests would be easier than for direct user activity. Federation stuff can be queued and then spread over time, but user requests cannot be.
My kbin instance’s data (text data, that is) probably takes up less than 8 GB right now, and I’ve had it running about two weeks. Media storage (which I do through S3) is around 5 GB so far. Kbin does do media mirroring different than Lemmy though (I think), so YMMV. I think Lemmy mostly links to the original instance’s media object as the source.
The main thing I found eating storage on my server was a lot of old Docker images (and volumes) from me trying to get everything up and running. If you are using Docker you could try doing a
docker system prune --all
to get rid of unused images/build caches (anything that isn’t running currently).