I have a difference of 9 still at level 19.  I get just over half a skill point 
per kill.  I easily play 16+ hours a day and have been at it for well over a 
week now and have 9800 SP. Level 13ish in the Ch'in tomb killing stone 
ghosts was some of the most efficiant farming (most points per hour).  
Also around level 16-17, the bandit camp is good.  In between these hot 
spots, you will spend days at a time grinding through different monsters.  
I grinded Yeohas for a long time.  The only de-leveling I did was at level 
11.  I dropped 60%.
Some pics of my journey.
 
My first suicide to delevel.
 
I killed stone ghosts so long, I was totally sick of them.  So I started
grinding Yeohas.
 
My need for a break from grinding lead me to climb to this spot.  After I
found this, I started exploring all over western China and found some
great places.
http://www.silkroadforums.com/viewtopic.php?t=1073
 
Still grinding on Yeohas.
 
4000 SP!!
 
I love these shots.
 
I concentrated on hunting Giants for a while to keep my mind off the #'s
and that worked really well.  Made it through another level.
After that we had the Monster Mash Event which also was a slight distration
from time to time.
 
One of my favorite screenies...nice night time shot =)
Well, glad I could share.