My experience (and I have a lot in this area) has been that Delta will normally issue a voucher for a fare difference on a domestic ticket without any change fee. That may not be true for internet specials, however. I haven't run into that yet. I currently hold three electronic Delta vouchers for fare reductions on domestic tickets. They expire after a year.

On international tickets, they insist on collecting the $150 change fee under all circumstances. Therefore, unless your fare drops by a very unlikely large amount, you cannot come out ahead. I have never succeeded even in starting a discussion of waiving this international change fee. It's not going to happen. Period.

Bruce