Anything wrong with this linear PSU design? (now selecting parts)

[Powermax]

On an unrelated note, I bought those transistors to drive a flyback transformer as replacements for some more expensive MOSFETs. I wanted to see how BJTs would compare to MOSFETs in this application. Those were dirt cheap so I thought I'd give them a try. I was disappointed in the results. 

Is there much I can do to reduce the Vce voltage and really drive them hard into saturation? I tried making a darlington but quickly found out that unless I use 2 of those transistors, then the small one will die (due to high voltage transients in flyback operation). Using 2 of them defeats the cost benefit of my favorite FTP33N25 MOSFET (a modern more-or-less equivalent to the IRFP250N with simalar ratings)

Interestingly, the TIP120 gave me amazing results!!!! (nice fat juicy white arcs, almost as good as the MOSFET), For about 2 seconds, till' it died. 


So I know of the darlington configuration, and the complementary pair, and after asking this question on Instructables, and I did receive a very interesting configuration shown below, but other than that, what other classic or common BJT circuits exist for high power switching?

[David Hess]

Is there much I can do to reduce the Vce voltage and really drive them hard into saturation?

...

Using 2 of them defeats the cost benefit of my favorite FTP33N25 MOSFET (a modern more-or-less equivalent to the IRFP250N with simalar ratings)
...

So I know of the darlington configuration, and the complementary pair, and after asking this question on Instructables, and I did receive a very interesting configuration shown below, but other than that, what other classic or common BJT circuits exist for high power switching?

Use different transistor types in ways that take maximum advantage of their strengths.  Use the PHE13009 in common base configuration and drive the emitter with a cheap high current low voltage n-channel power MOSFET:

http://electronicdesign.com/power/cascode-configured-gan-switch-enables-faster-switching-frequencies-and-lower-losses

[VEGETA]

FTP33N25 MOSFET

this thing has an SMD version, how can it be used in such designs? and also how to dissipate heat?