I have not worked with kexec or kexec boot enough to know if it will work.
pdaXrom is built with the kernel external to the rootfs. If I understand correctly kexecboot looks for the kernel located under /boot on the rootfs? (I dont know) If this is the case, then I know kexec boot will not boot a pdaXrom rootfs.
In with the new release, ubifs will be replacing jffs2 so unless kexec has been built to boot a ubifs, it probably will not work, even if the kernel was located under /boot
But I'm just going on assumptions :-), please someone correct me if I'm wrong.
Late