It's not an issue of brands, but one of design.
The following is copied from EHOW.COM

High Effluent Levels
Properly designed and maintained peat filters in a septic system will trap effluent in the organic material long enough to break down completely. However, if the system is not properly designed or becomes clogged, raw sewage and high levels of bacteria may contaminate the soil, according to the Center for Public Integrity. Peat moss septic systems are often installed in rural or hard to reach areas where there is no city managed waste water treatment. Homes in these areas often use the groundwater on the property for drinking water. If the groundwater becomes contaminated with the bacteria or sewage from an improperly working septic system, the home's occupants can become seriously ill.

Frequent Maintenance
Unlike traditional septic systems, where maintainable is usually required every three to seven years, peat moss septic systems may require treatment as often as every three months says the University of Minnesota Extension. Clogs may develop in the peat moss material from a peak load of water or waste. These clogs prevent the waste from moving evenly through the filter materials. Regular maintenance prevents build up and ensures that the system is not being flooded or overworked. Maintenance visits often include lab testing of bacteria and waste levels and can become expensive, raising the overall cost of this form of septic system.

Overflow
All septic tanks are designed to handle a specific amount of waste water, and will become damaged or flood if more is regularly added according to Enviro-Access. Peat moss systems require a specific amount of organic filter material for each gallon of water that will enter it each day. Many homeowners are unaware of their water usage, and may purchase a system that is rated for 200 gallons a day when they produce 300 or more. Extra waste water may run directly into the soil surrounding the filter without the waiting period that allows for the breakdown of waste materials, creating a hazard. Excess water use also leads to flooding. Flooded septic systems become clogged and must be completely cleaned out in order to work again.

Finding a Disposal Site
Eventually the peat moss filter material becomes too compacted or broken down to treat the water coming through it. At that time it must be removed and new peat moss is added. Finding a safe place to dispose of the bacteria filled used peat moss can be difficult due to many state's prohibition on putting materials that have been in contact with human waste in a landfill, notes the Center for Public Integrity. Homeowners may have to pay for the materials to be buried or shipped to special treatment facilities. Peat moss must only be replaced every 10 to 15 years if the system is designed properly, but if it floods or some other unexpected system failure occurs the peat moss must be completely replaced.

You hsould check with your local health department and the state agency that oversees them to see if any peat units are approved for permitting or if the entire system has to be designed by an engineer. As far as maintenance costs, that will depend if it's a gravity system or pressurized dispersal. Here in NC, such systems also require twice yearly maintenance visits from a certified operator and an annual inspection from the health department