FWIW, the owner of Boundless Performance wrote me back in response to an inquiry about their harness. Here's what he said:
"If we are comparing like for like, we developed our bag to be similar to the Vortex Guide Bino. The difference is structure. Our bag is more lightweight, and flexible, while still being able to protect your gear. Vortex on the other hand is more firm, meaning it keeps its shape well even with some force. That being said, we are able to offer a lower price because of our choice to make the bag a bit more flexible and lightweight. If we are comparing features, they are virtually the same, just the price is different. I have a lot of customers who say they enjoy the bag, that it's very similar to vortex and other big brands, and they were glad they purchased it. On the other hand, there is a small percentage who rather pay more for higher end features such as magnetized enclosures and firmer material. "