Rebuilding the World Question

[Bart Silverstrim]

Here's a definite question from a first timer, but there are so many 
variations out there that I thought I'd bounce this off the list and 
see what people thought (if I was doing this "correctly")

I have a 4.9-RELEASE installation.  It was recently pointed out to me 
that to get all the bug fixes and security fixes, I need to cvsup with 
"RELENG_4_9", not "RELENG_4_9_0_RELEASE".   So...here's the src-supfile 
I am using:
*******
*default host=cvsup7.FreeBSD.org
*default base=/usr
*default prefix=/usr
*default release=cvs tag=.
*default delete use-rel-suffix
*default tag=RELENG_4_9

src-all
doc-all
*****
(does the tag=. matter here?)
I run it with
cvsup -g -L 2 src-supfile
glance over /etc/make.conf
cd /usr/src
make buildworld
make buildkernel
make installkernel
reboot into single user mode with "boot -s"
mergemaster -p
make installworld
mergemaster
reboot into normal multiuser mode

One source I found said that they allow mergemaster to pretty much 
overwrite files unless it is asking about
/etc/passwd
/etc/hosts
/etc/groups
/etc/master.passwd

This is an update from 4.9 release to the (hopefully) security updated 
version, and the system is running a generic kernel and is a pretty 
stock install (some ports are in place, but port updates are done 
separately, as I understand it)

Are there any steps or pieces of advice I'm missing here?  
Advice/explanations/etc. are all appreciated.  Thanks!