Martin,

I just studied the LT3750 device. It is similar to the one I already tested but nevertheless I ordered some samples too. Same for the coils from coilcraft. Let's see what will come out.
The device I used was a MC34063. The min. time I found to reach 200V was about 6 ms with a several self-made transformers.
I expect better results from the LT3750 because of the tuned coils for the LT device.

Hope the parts will arrive within the next 2 weeks.

Best regards from Germany

Uwe