I upgraded recently from a5comm to a6comm, and I can tell you that the engine itself seems indeed to have gotten better. If they will, besides shaders, implement bumpmapping for the levels it should be worth the money, (if you'r not too short of it.)

As far as the editors are concerned though, they still are the worst I ever payed money for.
WED in not handy and does sometimes very queer things. (as does MED)
You can use it, but it is not really good.
MED is absulutely useless. They are not worth it.

So if you'r only interested in the engine it is ok.