It sounds like Mike has thought
all of this through quite thoroughly. As furfly has been in the
ACS hosting business quite some time, going with his instincts is
probably a good thing.
If it were my job to do, I would do it the same way. In fact, I
have done migrations on RAID the same way, keeping one of the mirrors
for archives and for an emergency "everything else broke"
reboot/recovery disk.
The only thing I would recommend is that a specific time that is
convenient to Mike be scheduled well ahead of time, with a prominent
notice on the web page and a post made to all forums (so that everybody
who gets notifications can be notified even if they don't visit the
site regularly). Then we all know to expect the downtime, which
will probably be several hours even if everything goes perfectly.
From reading his post, I am quite comfortable with his ability to perform this.
On another issue, I am of the opinion (having sysadminned for 15 years)
that there be at most three people with administrative rights.
These three people need to be in physically separate areas.
These three people need root, either directly or via sudo. These
three people need to be able to work well together and be able to agree
on sysadmin style, etc. If Mike just wants to be the physical
machine's admin, then I suggest that at most three core team members
(or core team designees) have root access rights.
More 'cooks' than that is a recipe for trouble. No, I don't want
it, either 😊. I have root on too many machines already.... 😊
For specific admin access, others could be members of groups with
access to directories and files for specific uses. But more than
three roots can easily cause trouble.