Would this work to lengthen shoulder strap?

Im trying to figure a way to lengthen the the shoulder strap on my classic Messenger Bag. I saw this replacement strap,http://www.timbuk2.com/tb2/products/a..., and was wondering if it was the same material as the Messenger bag shoulder strap and if it is the same width. I know a seamstress that could sew the 2 straps together. I dont mind spending the $10 on the strap if it doesnt work, i just want to make sure the straps look same before i order it. Thanks