Yeah. HT's nice because they almost seem to add details that weren't there. This isn't a bad thing as long as they fit. But with Big Chap, not only did they made a more elaborate figure (which is cool), but they totally changed the shape of the mouth and dome. Other than that, gorgeous paint and body. Heh, same goes with their Berserker. I dunno what's been up with them lately.
Basically the only things that would make the Medi Alien truly perfect IMO would be:
1/6-scale
More sculpted body detail
More elaborate paint work (just for kicks)
Even so, I'd say the $100+ price tag is justified by the fact that the overall shape is perfect. I look at this guy and can safely say "THAT's the Alien."