I've been growing lettuce and other leafy greens in (galvanized steel) gutters for two years now, and I've thought about using them for strawberries. A couple issues to consider:
1) The ends of the gutters can be hard to waterproof, since they are not designed to be; the gutters are intended to slope away from the ends. I used tape (on the inside surface) which has not held up well. If you use the gutters as intended -- flowing toward a downspout -- rather than making them horizontal and drilling drain holes as I did, you may have better luck.
2) The soil in the gutters dries out very fast, even with full mulch. Plan on watering the plants every day during dry weather.
3) One of the chief advantages of planting in gutters is protection from
rabbits and other ground-based predators. If your strawberries' main predators are birds, they may not be safe in hanging planters -- you may have to hang nets during berry season.
Personally I would not be concerned about either aluminum or steel leaching. Most PVC doesn't hold up well to sunlight (UV) even if it's marketed for outdoor use, so it fails from a durability standpoint regardless of its other properties.