Donwside to 2: Your VM becomes harder to move between hardware, you lose snapshotting capabilities from a copy-on-write image.
5 is flexible, but has limitations. For example you wouldn’t want to run databases on NFS volumes.
If initialization time is the only problem with 4, you could create several smaller images on the disk. Create the first one, initialize the VM and set up an LVM volume on it, then start creating more volumes and extend the LVM volume.
Time to piss off both camps an start calling it f5x.