The persistent-subtext=... bootoption supported by live-initramfs provides 
assignment of different persistency partitions for different live systems, 
which would be nice to have for 32bit vs. 64bit, full vs. medium vs. small, 
different versions of it, etc. - see http://bugs.debian.org/cgi-bin/
bugreport.cgi?bug=536728

We should discuss whether automatically setting persistent-subtext=... would be 
an option for grml2usb. Definitely needs further discussion, just submitting it 
as bugreport so we don't forget it.