Pairwise summation is definitely a useful technique, depending on your situation. However, it does have the key limitation that you need to have all your data b

Pairwise summation is definitely a useful technique, depending on your situation. However, it does have the key limitation that you need to have all your data beforehand. There are quite a few cases in practice where you have streaming data, and Kahan summation handles this just fine. In addition, if your data is really unbalanced in it's magnitudes, pairwise summation can still lose a fair amount of precision compared to Kahan summation. There are definitely cases where you'd want to use one, and cases where you'd want to use the other.