We present Lynx-robot, a quadruped, modular, compliant robot. It features an either directly actuated, singlejoint spine design, or an actively supported, passive compliant, multi-joint spine configuration. This study aims at characterizing these two, largely different spine concepts, for a bounding gait and a robot with a three-segmented, panthographic leg design. An earlier, similar-sized, bounding, quadruped robot with a two-segment leg design and a directly actuated, singlejoint spine design serves as a comparison robot, to study the effect of the leg design on speed and cost of transport, while keeping the spine design fixed. Both proposed spine designs (single rotatory, active and multi-joint compliant, activesupported) reach moderate, self-stable bounding speeds, with comparable power consumption values. Power measures indicate an advantage of the three-segment, panthographic leg design compared to the earlier shown two-segment, compliant leg design. I