Well first of all whats acceptable to you? Its kinda different in everyones mind...
For me a Impulse of no less then 25 is the bare minimum, and 30-35 is good enough for me on a DN classed ship.
And a manuver rate of 0.70 minimum is also good. Ive had a DN loaded with weapons, shields 7 and One 8 4 Quantums 1 photon , warp IX and it had a max speed of 35.XX and 1.05 manuver.
And i agree with garreth, zooming 'jets' just dont seeem like star trek.... You know, big ships are lumber beast, while smaller are always agile and speedy. And if its a player who strips all shields off, cause for speed then thats a thing they can do. And u can feel good cause You have shields while ur oponent doesn't. Hull damage anyone?