Now, I have automated the creation of Service Packs, PET packages to upgrade an already-installed Quirky. That is, when I release Quirky 6.1, the Service Pack to upgrade from 6.0.1 will automatically be created, and also uploaded.
The Service Pack will be quite a small package. In the case of 6.0.1 to 6.1, it is about 23MB, as I have bumped the kernel from 3.12.2 to 3.12.6. Maybe some future upgrades will be very small.
The Package Manager checks for availability of an upgrade Service Pack every time that it is started.
However, I have also created an entry in the Filesystem menu, "Quirky Version Upgrade Manager", so a user can check for an upgrade whenever they want, perhaps in response to seeing it announced on my blog.
An installation of Quirky should be upgradeable indefinitely by means of Service Packs. Being a full installation, there are none of the complications that limited adoption of this method in Puppy Linux.
On the otherhand, there is a slight complication in that the upgrade is taking place in a running Quirky system (though, a reboot is recommended immediately after an upgrade). I might, in future, do it the reboot -> ramdisk way.
The Service Pack upgrade will work for Quirky installations in a drive (ex, Flash drives) or in a HD partition.