Clearly there is a lack of gain on the high side of your sim.  The key to debugging this is to examine the currents in the transistors.  May be a bad model.

If you post the file and models I could try it out. Which simulator are you using?

PS:  Here are some voltages and currents off my sim attached.  I hope it will give you some ideas.

Sorry for the necrobump.

The posted schematic will not render correctly.  I guess it has become corrupted.  Can someone post a clean copy? 

Thanks

Well I'm not ignoring you but I don't have an answer either.  I haven't come up with anything suitable in a compatible package, or even a SM package for that matter. Can you relax the specs e.g do you really need 10W @ Tc=25C?