The fast modulation characteristics of quantum cascade lasers (QCLs) up to the MHz-/GHz-range give insight into their dynamical properties and act as prerequisite for experiments like injection locking of mid-infrared frequency-combs or spectroscopic measurements. In this paper we present the first analysis of the optical high-frequency modulation characteristics of surface-emitting mid-IR DFB-ring QCLs up to 160 MHz. We compare them to DFB-ridge QCLs from the same gain material and show the existence of the (quasi-)single-sideband regime, a special FM-state in QCLs, not present in regular diode-lasers. Surface-emitting ring-QCLs are particularly relevant with their potential in array integration and monolithic laser-detector-schemes.