idg/avman, apologies for both my tardy reply and any confusion, been on hols and don't have manuals for all msn's at home. I seem to be on the 321 most of the time but went in to work today and tried it on one of our new cfm engined 320's, and it is as you say idg, still only half speedbrake available on new 320 with a/p engaged. I had been told that this only applied to our older v2500 engined A320's but it is definitely on all of our fleet. I popped out the a/p and full speedbrake was available, so it does seem as though only the a321 has full speedbrake available with a/p engaged for the 319/20/21 family.
Regards, Scally.