I noticed this too when I ran a character through for the set. It's a little unnerving to hear a different voice. I didn't see any dialog changes in Sunrise, are there changes in the next mission? If not, why the change?
I like both the shepard and engle classes. However, after seeing it in-game, I dropped all consideration for buying the europa and decided to hold out for the shepard. It's definitely more of a "hero" ship.