My family and I are based in Taiwan, and since we prefer nonstop flights, we fly Eva almost exclusively. We expect to earn around 20k-30k miles a year, which is enough to maintain Silver status on Eva. However I've also learned that we could likely get an easy *A Gold status if we credit Asiana instead.

On paper, *A Gold gets a lot of nice benefits that IML Silver does not, and IML's award redemption chart seems to be among the worst. However, given that we are unlikely to fly other carriers, are there some ways in which Eva gives preferential treatment to its own IML Silver members that might make it worthwhile to stick with IML instead?