Dear grizedale
Hi
Fly back converter , has bad out put spikes and regulation ratio . and you can not get the out put power , more than 350 watt with best designing ! . but the forward converters can give you powers up to 1KW with good ripple rejection ratio (load regulation) . and without bad output spikes(approx) .for more information and designing methodology , you can read books in this field , such as switching power supply design of abraham i press man , or switching power supply cookbook of marty brown or .....
Best Wishes
Goldsmith