This paper presents a theoretical and experimental assessment of the performance of a wavelength converter based on semiconductor optical amplifiers (SOA) in a MZI configuration for optical label swapping. The optical labeling of the signal is based on an FSK/IM combined modulation format for the header/payload, respectively. Experimental results are presented for a signaling scheme with payload data at 10 Gbit/s and an FSK label at 312 Mbit/s. Simulation results and measurements of the chirp properties of converted signals operating at data rates of 2.5 and 10 Gbit/s are presented. Conclusions and design guidelines are presented regarding the implications of the wavelength converter performance on the quality of the label and payload signals for fast packet/burst forwarding in optically labeled switched networks.