[mcmancini]

It's true that Ti rings are harder to cut, but the equipment to cut them is standard in American ERs. It still takes longer though. Even worse are the newer cobalt chrome rings, those take forever to cut off even with the right equipment. Safest of the alternative materials is probably the tungsten carbide or ceramic rings, since those can be fractured off with a pair of common vice grips. Don't know what happens when you're traveling in an area with a less developed medical system. If you aren't at risk for anaphylactic swelling, don't work with your hands, and don't travel in undeveloped areas, the risk of this sort of situation might be low enough to not worry too much about.

A more practical problem with alternative materials is that they can't be resized (some jewelers will resize Ti a little, but it's challenging). The alternative materials are cheap enough that you can buy a replacement that's the right size, but if you're sentimental (and a wedding band seems like something one might be sentimental about) it's a problem.

There's nothing wrong with alternative materials, it's just that sometimes the drawbacks are overlooked while being dazzled by the advantages.