I have one of the smaller ones. They are .....OK. shrug? Not great, the plastic is a FAR cry from a Pelican case. They do have a gasket and claim watertightness. I would expect more water resistant than tight. Good for humidity and rain/spray, where pelican cases are submersible. HF's stupid "pressure equalization valve" is a threaded plug with an O-ring, so that's much worse then Pelican's valve.
I actually have one of the real milspec Pelican brand rifle cases and don't like it. It's a great case, but for the amount of rifles it holds, it's heavy and bulky. Since I'm not actually locking out of a Swimmer Delivery Vehicle on my way to the range it tends to be WAY more trouble than it's worth. (single exception is commercial air travel, but nothing screams "I have cool, expensive rifles!!" like a Pelican rifle case).
In all, based on my experiences with the more briefcase sized HF case, compared to the Pelican I also have, you will get all of the weight and bulkiness, and about 50-60% of the water and impact protection of the real thing. Up to you if that fits your needs.
ETA: Almost forgot, the foam in the HF case is no where near as good as the real stuff. It is both less dense, and seems to absorb oil/stuff more. I suspect it will break down a lot faster and be the first thing that fails.
