Jumping in a little late and plenty of good points have been covered, but a perspective I thought might give you some ideas is grocery store brand products.
Consumers know it's not the real deal, but they do everything possible with the packaging to make the products look identical on the shelf and get people to focus on the price. Example kroger brand ibuprofen vs advil.
When you're sharing the same shelf space that strategy makes a lot of sense sense, but when people are comparison shopping on your site I'd agree to not mention them by name if the angle is that your product is the same, but cheaper. It just gives them another chance to work against you with their established branding. I'd focus on why your product is superior and let price speak for itself.
So maybe you could take this approach through a 3rd party? Get a comparison site/blog/etc to do a heads up review?