firstly, Carbon Dosing and Biopellet are the same thing, they both provide food (organic carbon) for bacteria too feed off in order to reduce nutrient.
Secondly, if the directions are not followed, and a system is not run as it is supposed to be, ANY form of nutrient reduction can go south and crash a system.
Saying something as broad it is "very easy to crash your system with biopellets" is of course correct if you dont understand the dynamics of the system, and know exactly how it works, but this is true for any form of nutrient reduction if not run correctly.
If you are also considering running Roawphos again, it is a fair, and almost unequivocally absolute sign that you are nitrate limited. read my blog post here for more info.
http://wateralchemy.blogspot.com.au/2012/03/nutrient-reduction-using-organic-carbon.html
In essence, weather it is miracle mud with a refugium and macro, liquid/solid(biopellet) carbon dosing, rowaphos and deep sand bed, or whatever the system may be that you are using for nutrient reduction, RESEARCH RESEARCH RESEARCH.
Even if there is scientific data on the system, NOTHING, i repeat NOTHING compares to seeing actual results in peoples tanks, and seeing the results in your own tank. If your not comfortable with the system, don't use it, but if there is sound evidence showing that it works and you understand the scientific principals behind it, then by all means it should successfully work for you.
But whatever you do, DO NOT dismiss a system or approach just because you havent used it, or there have been a few bad reports on it, most of the time you will find these bad reports and opinions will come from people who 1. havent even used the product 2. have used it but not applied it properly or 3. and this is connected to the last statement, have applied it, and not understood the dynamics and functions of the given system for nutrient reduction.
nitrate limitation when carbon dosing (especially biopellets) is a prime example of 2 & 3.
Dismissing things we do not properly understand, weather we have used them or not, is a SURE AND INEVITABLE road to failure