I love my dark silver and i have to say that it's probably the one of my Chanels i use the most. I find it goes with pretty much everything. I suppose it is trendy, but really metallics come and go all the time - like animal print really. I have had some of my other metallic bags for years and they go through stages of being used less or more, but they will never be "out" of fashion.
i say go for it. Too boring and safe to stick to black bags all the time. Silver is a neutral and will light up an outfit.