I bought this to be able to transport my resonator. It's solid brass and weighs over 12 kg with its case! I've tried gigbags for it, but the weight literally pulled the backpack straps or zippers apart.
Using the Ortega Back Pack Strap De Luxe I was able to ride my bike to the train station and then travel my guitar to another city, no problem. While I don't think I'll transport this very heavy instrument often, I have enough confidence in the Ortega that I plan to use it regularly to transport a valuable classical guitar.
One note: When I first received the product, I was concerned because the straps slide quite freely in the clasps. But once you adjust them on the guitar its weight holds them firmly in place. You should plan to spend a few minutes finding the best adjustment for your case.