Software Transactional Memories (STMs) are emerging as a highly attractive programming model, thanks to their ability to mask concurrency management issues to the overlying applications. In this paper we are interested in dependability of STM systems via replication. In particular we present an extensive simulation study aimed at assessing the efficiency of some recently proposed database-oriented replication schemes, when employed in the context of STM systems. Our results point out the limited efficiency and scalability of these schemes, highlighting the need for redesigning ad-hoc solutions well fitting the requirements of STM environments. Possible directions for the re-design process are also discussed and supported by some early quantitative data.