Just an fyi for those who have not tried to convert a 32bit system to 64bit yet.
Prompted by a hard crash that would not let me mount the root lvm, I decided to take this opportunity to simply move forward to the 64bit version of SME8 in order to prepare for some future 64bit requirements that I have.
My first attempt was to simply try to do an "upgrade" via the installer. This really didn't work out well. The system ended up confused about appropriate paths for the 64bit libraries vs the 32bit ones. The first thing to fail in fact was yum.
Rather than try to figure out why and likely just find a longer list of issues, I decided next to do a fresh install with 64bit and then do a "Restore". I used the Upgrade from Disk procedure in this case documented in the wiki.
This latter strategy worked quite well actually!
I was a bit concerned that there may be some architecture dependent items in the sme database but I have not yet encountered any issues. Given I was dealing with a crashed system, I was not able to do a pre-backup event so I simply copied over the mysql databases as is and then regenerated the mysql root password.
Hope this helps someone else. If I find any issues, I will report back. Once we have some collective experience, we can create a wiki entry.