I just did it a couple of days ago. It’s just under 3 GB.
Which matters a lot on the only 2.5Gb sized rootfs. It’s not working well if you want to put your FLAC music collection on the rootpart 
But since Sailfish apps are mostly small, I can’t see myself ever exceeding the size afterwards, even after multiple updates. If Jolla would make the rootfs 3GB in the first, most people would probably never run into the problem.
If you still need more, either shrink your home and add it to the rootpart or use SDcard space, add it to the volume group and extend the rootfs.
2 Likes