[CentOS-virt] Migration checklist

Is there a current list of the required "matchups" to migrating guests from one Xen host to another?

I doesn't appear to me that paravirtualized machines have much in the way of obstacles. Hardware doesn't seem to play into it. What about Xen kernel matchups, say from a Xen 3.4 to a Xen 3.1?

How fussy is the HVM migration? Would moving an HVM from an AMD64 Athlon X4 AMD chipset to an Opteron X4 nVidia chipset have issues? What about a "hybrid" HVM-PV, like Windows 2008 with GPLPV drivers installed and where you have installed to a chipset as an HVM and then swapped to a PV?

I'm going to begin trying, but some time-saving tips, or a checklist, would be welcomed.