Spearhead wasn't very good, neither was Breakthrough ... in fact they just got worse and worse ...
It's actually a bit strange. I played Spearhead immediately after it was released and thought it was raping the MoHAA. So much had been changed and generally the worst expansion pack I've ever played.
But with Breakthrough it was a return to the integrity of MoHAA and it actually added some new exciting levels and environments.
But I've spoken with another person and he says the same as you txa/Mike.
vh. Asbjørn