As best as I can tell, Chimera is about 11.5" tall. He definitely won't reach 12". Here are his expected jump heights (and other obstacle heights) for the agility venues that hold trials in our area:
AKC: 12" jumps (8" tire jump, 24" broad jump, 8" pause table, 5'6" a-frame)
USDAA: 12" jumps for championship program (20" broad jump, 12" table, 104 degree a-frame?)
CPE: 8" jumps (16" broad jump, 8" table, 5'-5'3" a-frame)
NADAC: 12" jumps (4'8"-5' a-frame) (note: NADAC has no teeter, chute, broad jump, or table)
TDAA: 8" jumps (8" tire jump, 6" table, 3'8"-5' a-frame depending on length of boards)
I've been jumping him at 8" so far, since I thought that would be his more common jump height. Time to raise it up!