I think I was one of the ones to jump on the pellet bandwagon before most others did and I took them off line just about the time when everybody else started getting their reactors and here's why:
The things I like to keep like to eat (who doesn't!?) so my system is set up to supply food on a continuous basis (Powdered foods for seafans, sponges, filter feeders. etc.). About 8 hours per day food is dispensed slowly into the tank.
And that's the reason I even got the pellets. I am not keeping a low nutrient system.
I also was hoping the bacteria from the pellets could be used as food for my corals.
With my constant supply of food to the tank the bacteria used it in the water column causing an almost permanent bacteria bloom. None of the corals liked that. They certainly didn't seem to be happily eating the bacteria.
Sure N and P were super low but at what cost.
At some point I got so sick of it that I turned on the UV sterilizer (a 'don't do' for pellets) and within a few hours the tank was clear, the corals looked happier. My choice was then to either replenish the pellets in the reactor and keep the sterilizer running to ensure the bacteria only did their work in the reactor and not in the water column, to quit feeding round the clock or to simply do away with the pellets all together.
By that time I already knew that 50% of the reason I wanted the pellets to begin with didn't work for me: none of my critters cared to eat the bacteria stuff. Stop my automated feeding regime would have meant giving up on my intent to keep my critters fed as close as possible to how they are fed in the ocean. The cost to replenish the pellets in adequate amounts to keep up with my stuff seemed really high and so I decided to take the reactor off-line.

Ricordea finally started to puff up and split, gorgonians started to have their polyps out all the time, encrust the rocks and grow. Things looked better and that was really my decision maker right there.

At least for my type of set up the pellets were not a good fit (mostly due to my continuous feeding I am sure)