One the thing I like about the Sinn Silicon strap is how it fits against the watch case and is shaped to keep the watch central on the wrist.
Actually, that's the only thing I like about it. As such, my UX spends its time between an Isofrane and a two piece NATO.
Now I have another option: The Elliot Brown Rubber that came fitted to my Horton, but is available separately for £55 in the UK and comes in a range of colours.
It was a moment of 'I wonder if that will fit...' and tbh the spring bar took a bit of a push to get in place, but I think it looks OK. It's comfortable and not as sweaty as the Sinn strap. It also tapers so isn't quite as bulky.