Oh dear! I guess I'm back on my soapbox! I just can't seem to help myself.
I'm a big believer in martingale narrow and light weight rolled collars for Shelties.
Flat collars of any material can mat the fur, particularly if they are fixed collars.
The problem with fixed collars on Shelties is they have thick ruffs and small heads. To size a regular collar onto a Sheltie neck requires either that you make it too tight (hence the matting) or too loose (hence slipping the collar).
Martingales are ideal for Shelties. These are NOT choke collars. Your martingale should be sized so that it hangs loose when not attached to a lead. When attached to a lead, it fits a little tighter around the neck than a regular collar, but only when they pull on the lead.
If they try to pull, it pulls tight enough to avoid them slipping the collar (because of their small head in comparison to their size).
Rolled collars are better than flat collars whether martingle or standard. They just matt less.
Of course, you can avoid the problem of matting if you only put their collars on when they go outside. Frankly, having a Houdini dog myself, my dogs wear their collars 24 x 7. But they are no crated anymore.
I understand the arguement for keeping collars off while dogs are crated....but I find it difficult to see how a dog could strangle himself with a martingale, even if somehow he managed to get the tags latched to the crate (remember, the collar is LOOSE unless attached to a lead. Even if a tag caught on the crate, the dog might be uncomfortable but would not strangle.
Like Chris, my dogs have custom-made, leather braided kangeroo martingales. Unfortunately, the maker that both Chris and I used is not accepting new clients currently.
But I encourage you to google "braided martingale collars" and see what you can find. I think the sample your showed is ok, but a little heavy
I did find this links, but can't speak to the quality or anything else....
http://www.custombraidsbycarrie.com/martingales.htm
If you scroll half way down this page, you'll see the photo's of my dogs collars made by Leashes by Design (who is no longer actively in business). Look for the post by Barbara Vachon
http://www.leashesbydesign.com/Testimonials1/Testimonials2/Testimonials2.html
I hope this helps!