I recently purchased both the stainless and aluminum backplates from Hammerhead Scuba, and their harness kit as well. Very happy with the purchase, the quality of the product as well as the service. Had a question on my order and was immediately contacted by Ed.
So far, I have only 1 dive with the aluminum backplate (single steel 95, no STA, freshwater) I was hoping for more dive time before giving a full review, but given that it's a metal plate, I don't know what would really change over time. Maybe the rate it chews up harnesses?
The backplate design is solid. The SS BP is impressively heavy. The multiple mounting slots are nice, especially compared to fixed mounting holes that other BPs have. I did not have to de-burr the BPs, though I did for the STAs (eventhough Ed says he dives with his raw, I chose to differ). The bends at the bottom are a nice ergonomic touch, but isn't necessary for me.
One aspect of the design that I particularly like is the STA, and how it offers a lower profile than other STAs. The Hammerhead channel is a little deeper than a Dive Rite BP (the other BP I dove), but feels just the same in the water.
I was pleasantly surprised by the harness kit. It comes with the thicker 6mm D-rings and locking keepers. Plus, enough hardware for 2" crotch strap with 2 D-rings. IMO, this showed that Ed wanted the best hardware for his kits, and wasn't willing to skimp. Heck, it even includes a bungee.
My recommendation, pull the trigger. Great customer service and great product.