IDP Help! CB or S?

Ok, my league has a bit of a whacky scoring system. We can start 3 DL, 3 DB, 3D.  In the 'D' spot, we can play any defensive position (I currently have 3 LB's in that spot).  In the 'DB' spot we can play Safeties and CB's.  And DL we can play DL's.

I'm trying to come up with the best strategy for my roster.  Who scores more points generally "S" or "CB"?  I currently have 3 safeties in my DB spot (Y.Bell, K, Chancellor, D. Whitner).  Here are some available FA's: Kyle Arrington (CB), Jason McCourty (CB), Chris Houston (CB)

Any help would be appreciated!!!!!!!!!!

Here's the scoring system:
Tackle Solo: 25
Tackle Assist: 10
Sack: 75
Interception: 150
Fumble Force: 75
Fumble Recovery: 100
Defensive Touchdown : 300
Safety: 100
Pass Defended: 50
Block Kick: 75
Turnover Return Yards: 1 yards per point

Since interceptions are worth a TON relative to other positions, I would assume CBs score more points than safeties in your league. The problem is the production of cornerbacks is harder to predict and less consistent throughout the year. I like McCourty the best out of the three you named though and would start him over Whitner.