first, i have much less knowledge about OS/Linux then you!
I installed first OpenSuSE11.0 and later CentOS5.2 (both use the same /boot which is on a separate partition), had a "similar" situation with setup (hdx,x) which also was succesfully but with additional info "something wasn't ideal but no tragedy" and if i remember right i solved it later with editing the menu.lst of SuSE
I think-agree that after reboot you should have GRUB with GRUBshell as you described. (buffer-cache become consitent with quit-reboot)
I read, that if the /boot-partition is a separate one with a filesystem different than the filesystem of the /-partition (e.g. ext2 and ext3) so we should mount it after having done chroot before and so GRUB can recognize it, otherwise it could cause problems for GRUB in stage1_5, where he will hang himself. (is only a uncertain idea about!)
I'm sorry for my english. Best regards
I read following too somewhere:
What you should be careful about is buffer cache. grub makes use of raw devices instead of filesystems that your operating systems serve, so there exists a potential problem that some cache inconsistency may corrupt your filesystems. What we recommend is:
If you can unmount drives to which GRUB may write any amount of data, unmount them before running grub. If a drive cannot be unmounted but can be mounted with the read-only flag, mount it in read-only mode. That should be secure.
If a drive must be mounted with the read-write flag, make sure that no activity is being done on it while the command grub is running. Reboot your operating system as soon as possible. This is probably not required if you follow the rules above, but reboot is the most secure way.
In addition, enter the command quit when you finish the installation. That is very important because quit makes the buffer cache consistent. Do not push <C-c>.