Boost PFC: Mode of control

[ocset]

Hello,
We want power factor correction for our offline, 230VAC, color changing, flashing led light. The power level is from 25W to 150W.
We want a boost PFC followed by two 75W Buck converters. These   lamps will sometimes flash on and off at 2Hz (150W to zero watts)
We  must tolerate the slow feedback loop of the boost PFC. However, we want the feedback loop to be as fast as possible and yet still achieve PFC. There is no hold-up requirement, and we wish to use the very smallest film output capacitance that we can get away with. The LED strings are 200V.
Also, we must be  PFC’d from 25W load to 150W load.

As such, we cannot use Critical mode pfc for the boost...because its operating frequency goes too high when we are at lighter load.....    .. We can mitigate this by using a very large inductor, but thats not wanted.
Also, getting PFC from 25W to 150W, and  having the PFC be as high in bandwidth as possible, means that  Fixed frequency CCM PFC is not so convenient for us, since tuning the voltage and current loops, for the maximum possible bandwidth of the voltage loop,  requires considerable care, and the exercise must be repeated whenever the output capacitance is changed or the  boost inductor value changes.
Therefore, we will use the L6562 Boost PFC controller  in Fixed off time control. 
Do you agree that this makes the most sense for our application?

L6562 DATASHEET:
http://www.st.com/content/ccc/resource/technical/document/datasheet/ba/de/2e/d0/3a/ca/4a/e6/CD00151385.pdf/files/CD00151385.pdf/jcr:content/translations/en.CD00151385.pdf

L6562 in Fixed off time control
http://www.st.com/content/ccc/resource/technical/document/application_note/cc/e2/9f/39/ad/27/4d/7e/CD00004484.pdf/files/CD00004484.pdf/jcr:content/translations/en.CD00004484.pdf