DB press or Barbell press for size?

Which is better, DB press, or barbell for shoulder size? I need a new shoulder routine so I was thinking

3x6-8 DB press
3x8-10 Lateral Raises
3x8-10 Front raises
3x8-10 thing where you grap an EZ-curl bar and lift it up to your chest.

Also, my split looks like this 14 sets for big muscle groups, 8 for small.

Monday Chest/Tris
Tuesday Off
Wednesday Back/Bis
Thursday Off
Friday Shoulders
Saturday Off
Sunday Legs/Abs

Now I'm wondering if I can get an arm day in there? I'm prone to overtraining as well, but it seems like my arms are lagging. THanks.

I love that split, there is almost no overlap, good to prevent overtraining!!! Adding more for arms would make it difficult though if you are prone to overtraining.

DB press is less stable so you recruit more fibres so you get more stimulation. Also there is no bar to have to get past your head. Its beneficial to do both DB and barbell, alternate.

I have an arm day..I put probably 1/2 inch on my arms since I started it

How long ago did you start it?

You might throw your arms (Bi's only) in on Saturday and move your Legs and Abs in with them. (Just a thought)