It depends on the criticity of your domain. Although it's unlikely to happen, Switzerland could decide on a whim to restrict access to .ch to Swiss residents or nationals. My guess is it's very unlikely with Switzerland but who knows? You can judge on the likeliness of that for yourself and act on it accordingly.

Realistically I think you're fine sticking with .ch, but consider one of the original gTLDs for future use (com, net, info, org)