Way To Secure SVN

So I just got SVN installed on my server, and now I'm wondering about the best way to go about securing it. This is what I've had done so far

the executables were installed to /usr/bin as ROOT

Then I created a directory in /usr/local/svn as ROOT to hold the svn repositories (the conf folders, etc).

I've decided that I'd like to use the SVNSERVE tool rather than have to run Apache2 which my current VPS provider does not provide any support for.

So I've run SVNSERVE like so:
svnserve -d -r /usr/local/svn --listen-port=7126

Then for each repository within the /usr/local/svn folder I've gone into the conf folder and added:

anon-access = none
auth-access = write
password-db = passfile
realm = myrealm

The passfile is located in the same directory (ie. /usr/local/svn/test) and contains my users in the format:

[users]
harry = harryssecret
sally = sallyssecret

I then run my checkouts like so:
svn checkout svn://mysite.com:7126/test

Now my question is how secure is this. I was tempted to use svn+ssh but I couldn't seem to figure out how to get it configured. Is the protection I have adequate? How easily can this be compromised? What steps should I take to lock it down further. Can I limit the connection to SVNSERVE to only come from certain specific IP's... similar to how apache does:

Order deny,allow
deny from all
allow from 192.153.123.12