A friend of mine asked the excellent question on why I bought an I²C 1-Wire expansion module for 300 SEK (about €30) when there are kernel drivers for using 1-Wire over GPIO right away and exposing the 1-Wire network below /sys/bus/w1/. I honestly didn’t know of this option!
Now I’ve made some investigations and realized that for example the DS2406 1-Wire chips I already bought are not yet supported by the kernel. There is a patch, for those who like to compile their own Raspberry Pi kernel. I don’t.
Also, OWFS seems to do an OK job of hiding the way of interfacing the 1-Wire network, so as long as use OWFS to access my 1-Wire stuff I should be able to switch to the w1 kernel drivers in the future.
For now, I will continue to use the I²C 1-Wire expansion module, because it works fine, I already bought more than one of them (!), and all my stuff is supported.