I have run Warner Marines ecoBak for the life of my tank for close to 3 years and have been very happy with them. I did however put them online right after the tank cycled, which I believe is why I have not experienced any issues with them. I feel like BP's have gotten a bad wrap because of people putting them on an existing system trying to fix a problem. If you dont truly understand what they are and what they are capable of, you can run into issues for sure.
Problems of stripping the tank of all nitrates and phosphates way too fast, starving your corals because you have been programmed to not feed heavily, not having a proper and capable skimmer to remove the bacteria that sloughs off and enters the water column which then can cause a bacterial imbalance, hence cyano. Tumbling the pellets too fast, adding way too many pellets too fast etc. All these things have been why BP's have received negative opinions. When the truth is, it has been more times than not "operator error".
Research and understand what you are about to add to your system. PERIOD
I have never seen a single sprig of GHA in my tank...EVER. I feed heavily upwards to 4 times a day. Pellets, flakes, mysis, cyclopeze, Rod's frozen, seaweed, reef chili, oyster feast and dose vitamins and aminos. My phosphates have read as high as 0.10 but never had issues with color or growth. Even when they stayed in the range of 0.05-0.08 for weeks on end. Nitrates are always undetectable, and my chaeto grows very fast. And all my zoas and rics and mushrooms do just fine along with my Acros.
I highly recommend them, but depending on the situation they need to be incorparated to the system in the proper way.