I know someone who lived in Korea and he raved about the underfloor heating system there. Does anyone know if this costs more to run than conventional systems?
The underfloor heating systems have come a long way. They are at the point where in some situations, they can be the primary heat system.
There is no one size fits all answer to your question. In many cases it can cost less-- but it really depends on your installation. Call a contractor and find out what is right for you.