I notice that hobbyists often try it because they want their SPS color to step up a notch. In general, it's quite risky and not worth the hassle. It must be started at a low level and increased gradually.

As far as I can tell, not many tanks use biopellets and even fewer use the other forms of Carbon Dosing, like sugar, vodka, etc.. In my opinion, it's just another of the many fads that I have seen come and go over the years, yet are continually resurrected by new hobbyists who think they have stumbled upon something exceptional.

This old fart prefers to imitate Mother Nature as close as possible. The same organisms that I have seen grow well in carbon dosed tanks do just as well in my tanks for less hassle, less cost and greater tank stability. I believe the reason for my success, if I can claim success, is the amount and variety of natural foods (natural carbon source) that I feed, including Phytoplankton and night feedings.

Sorry Ace to take this in the wrong direction. 

I'm still interested to hear others' opinions on biopellets.

It seemed like GFO was a good solution for a smaller/cleaner system such as mine. If I had a bigger system/with more of a load, I would probably lean towards biopellets.

Thats my two cents.