As noted previously, speedbrake deployment angles for 320 are:
AP Off: 3+4=40 degrees, 2=20 degrees.
AP On 3+4=25 degrees, 2=12.5 degrees
On the 319: With AP On or Off:
Spoilers 3+4 = 25 degrees, Spoiler 2=12.5 degrees in config 3 and 17.5 in all other configs.
So in effect full spoiler selection with AP on (or off - same thing on the A319) gives full spoiler deflection which however as an angle is equivalent to 1/2 spoiler deflection on the A320.
This is also why the spoilers don't work so well on the 319, especially when you forget you are on the 319 and accidentally only select 1/2 speedbrake with AP on, in effect you are getting a deflection of only a 1/4 of what would be available in manual flight on the A320.