I tried pellets a few months ago but my experience wasn't great. SPS colors were fading, pellets were clumping together, reducing flow - just didn't have the patience to tune the reactor.
I have used pellets ever since they were available on the market. The trick is to use a smaller percentage of the recommended for the size of your system and see how well it controls the phosphates and nitrates. The second thing is the skimmer is needed to remove the byproducts of the bacteria when they use up NO and PO in the system. The pellets need to be tumbling at all times bumping into each other for best results. It's a carbon source so the bacteria needs to not feed on the pellets constantly just enough to use up the NO and PO. Below is a old but great video that will help understand how they work and the best way to set it up. I personally recommend it if you want to feed heavily or use a specific food that you know will produce allot of PO an NO.