Tried out diakgcn on my 6870. All tests at aggression 12 and done over very short time periods, unless said otherwise.

Results:

2.5:
phatk_dia, WORKSIZE=128, VECTORS: 282 MHps (best one from previous test)
diakgcn, WORKSIZE=128, VECTORS: 278 MHps
diakgcn, WORKSIZE=128, VECTORS2: 279 MHps
diakgcn, WORKSIZE=64, VECTORS: 278 MHps
diakgcn, WORKSIZE=64, VECTORS2: 279 MHps
diakgcn, WORKSIZE=128, VECTORS2, AGGRESSION=10: 278 MHps (spiked up to 282 at one point.....)
diakgcn, WORKSIZE=128, VECTORS2, AGGRESSION=5: 275 MHps

2.6: (Sorry, did poor documentation here. Only listed best results If asked for I will document this better later)
phatk_dia: 272 MHps
diakgcn: 260MHps

tl;dr: diakgcn is currently slower for 6870