I wouldn't have the same actors for several of the roles (Bakula and Blalock would definately be replaced).
As for the character of Travis I did consider cutting him entirely, in favour of more alien diversity (which I personally find more interesting). In reality though he could resume his role at the Helm, with the increased rank and made more of an experienced character who has seen more than any of the other humans in the cast. As Yeoman though he would be on away missions with Archer, acting more as bodyguard than secretary, as well as being a certified pilot and general jack-of-all-trades, someone who could be counted on in a crisis, who Archer could also confide in when he needed to.
I do see what you mean about stereotypying though, but with a good actor and proper writing to boot then he'd actually come alive as a person rather than just a position.
In ENT I never really saw the point in the character as he never really did much. He could've been replaced by an extra and it wouldn't have had any impact on most of the episodes. I would hope to make him a little more involved in what was going on.