120W LED power CC, M:S ratio modulation

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Assuming that there is a PFC preceding this: would it be practical to use a topswitch (probably HX) in (probably, for good efficiency) a forward converter topology, and do mark:space ratio modulation, at 150Hz, of the offline converter itself to control brightness? (It is not acceptable to vary current in an analogue manner because of the change in colour temperature.) So far I have not been able to convince myself, from graphs of feedback loop performance, whether this is practical or not. Because the same power supply will also run the processor etc, the load will not completely switch off, but maybe switch between 60V 2A out, and 60V 10mA out.
Dear warysujoh: We do not recommend to use top switch in forward topology. To control the intensity of your light, you need to control it form secondary side as in DER-185.