Kasper,
I've got small wrists, and have found the Sigma to fit surprisingly ok - i do wear it somewhat higher on the arm.
Incidentally, don't write off the rubber straps - they are natural rubber and flexible and very comfortable. The Sigma is a pretty heavy watch with the rubber strap, never mind a steel bracelet - shame it was not made in the Ventura Titanox as this feels solid yet much lighter, and the Titanox bracelet is same design as that sigma steel bracelet pictured (I've put som emore pics of the mechanical Ventura watches i have in that forum, if you want to see the titanium bracelet).
The only issue with the rubber, is the excess left over is not cut off to fit, so there's overlap.
Best is definitely to try one on in person - these digital Venturas partcularly are tricky to anticipate how they will look on your arm as they are so different from the 'norm' ... and if anyone had suggested i'd be buying an orange strap i'd have thought they were mad! But when i tried it on....
Here's a couple of extra pics on my arm (in bright Bangkok sunlight)
a different angle, to show the 'fit' on the arm (incidentally, it'll probably take a while for you to get used to having the face set at the offset angle... it's odd at first)
rear view of the strap
If you do get the steel bracelet, i'd also get a rubber one while you're about it and while they're available.
Hope you find some Sigma's to try on!