The inductor is probably your problem. See the ringing in dannyf's simulation? This is due to the indutor. A well functioning PWM circuit will approach 100% efficiency, so how could adding an inductor boost efficiency?so the inductor is possibly the problem? I was hoping that the inductor was going to be an efficiency boost.
is there a reason FETS are preferred over BJTs in the 555 circuits?
FETs are preferred over BJTs because of lower "on" resistance.