Oops,
I always forget to remove the effect of pushing against a dealer blackjack.
After you have a blackjack, the chance that the dealer also has blackjack is:
(95/310) * (23/311) * 2 = 0.045327
Use that to revise the number from above:
0.005936 * (1 - 0.045327) = 0.005667
Total benefit of 2:1 suited blackjacks is 0.5667%