Upgrading from FC3 to FC4 and changing arch from 32-bit to 64-bit

[Joel Gomberg]

When I began the FC4 upgrade process, I received a warning from Anaconda 
that upgrading with a change of architecture was "likely not to 
succeed." I do have /home on a separate partition and have backed 
everything up, but I would prefer to upgrade because I don't know what 
kinds of problems I might run into with various configuration files in 
/etc.  My questions are:  (1) has anyone tried to upgrade from FC3 to 
FC4 with a change of architecture; (2) was the upgrade successful; and 
(3) if not, did this cause any problems with a subsequent fresh install?

It seems to me that I have nothing to lose by attempting the upgrade, 
since I should still be able to do a fresh install.  Is this correct?

Thanks.