Possible migration from i386 to amd64

[Oliver Bock <uvtcvruwickt@spammotel.com>]

Hi all,
I tested the amd64 (pure) environment some time ago and watch the list 
regularly. As we're reaching the point where almost all packages have been 
ported I'd like to think about a possible migration of an existing i386 
system. I can imagine that there a few (if not many) people out there who 
don't really want to throw away a working/configured installation... What 
kind of approaches could be used? Ok, at first there needs to be the 
descision whether one likes a "pure" 64bit system or not:

1.) 64bit kernel / 32bit userspace
It should be possible to change to a 64bit-kernel only without touching 
userspace right? Of course you can't use the "pure" 64bit version. Could 
there be a later upgrade to the next point ->

2.) 64bit kernel / 32bit + 64bit userspace
Is this possible AND sensible, having mixed mode userspace programs? How about 
the libs?

3.) Pure 64bit
This is my favourite way to go but how (if possible) can one change existing 
libs and programs to their 64bit equivalent? Will there be a kind of "apt-get 
arch-upgrade"?  ;-)

Please comment on this and correct me where I'm wrong. I'd love to hear of 
some feasable approaches hence avoiding to reinstall a complete nicely 
running system.


Thanks in advance, Oliver