Don't the 8th ed stealers have a 5+ invulnerable built in anyway? I was pleased to see many of the bigger boss bugs got fixed saves as well, nice to not be relying on psy power for that all the time.
Really like that Tyranid color scheme, BTW. Has me thinking about doing a "Film Noir" hive fleet where everything's in black & white. Maybe leave a little hard contrast colors here and there for effect - psychic glows, or shock-red blood splashes.