First, I would try here: Wintec Webbers Stirrup Leathers - Jeffers
Much cheaper. Their return policy says "If you are not completely satisfied with an item, simply return it in its original, unused condition within 30 days of receipt along with the original invoice and it will be refunded, replaced, or exchanged for you." I suspect you could get a pretty good idea of fit without actually using the webber by stretching it out next to your current setup and seeing if it would fold where you need it to fold.
My problem with the Bates webbers I ordered was that there just wasn't enough adjustment. I was in between their sizes, and my stirrup length varies with saddle, what I'm doing that day, the boot I'm wearing, etc. I also disliked adjusting them from the saddle - so I gave up and went back to stirrup leathers.