The earlier textures look more TOS-ish, the second ones look more ENT era. I like both!
You could release both, one as the prototype, and the other as the 'production' version with a stronger hull perhaps. (Would also explain the visual differences) And, if you do make a 'pirate' version (Perhaps by late ENT-era they're as common as the Batris type freighters) you could add extra hull plating etc.
'Course thats only IF you do a 'pirate' version.
Love it so far!