Internet traffic is continuously increasing. To accommodate this increased traffic, the optical transmission rates are moving from 40 Gbit/s to 100 Gbit/s. However they can also coexist in the same fiber. The crucial premise for network providers choose the transmission bit rate is cost efficiency. The Capital Expenditures (CapEx) are of paramount importance at the network design stage. However, due to the increasingly stringent economies of telecommunication networks the Operational Expenditures (OpEx) are becoming of greater relevance. Within the OpEx the cost related to the power consumption and the floor space (footprint) rent are the most influential parameters. In this work, we compare the Total Cost of Ownership (CapEx+OpEx) of fixed and flexible grooming architectures employing single or mixed line rates, and evaluate its dependence with the traffic pattern. Keywords: grooming, CapEx, OpEx, power consumption, footprint requirements.