I have found out that Hit-And-Run attacks with the defiant in KM1 is a fair tactic...
The defiant has the advantages of being able to move fast enough to avoid Photons and Quantums, even at very close range, while being able to kick some serious b*tt with the forward weapons.
Against large ships, such as the Excalibur or Sov / Neg'var, that are relatively slow moving, take as much as you can energy away from the sensors, punch up to weapons and engines to max and shields to whatever is left. Now you can go head on firing pulse weapons at a slow pace, so you can see the shields at all times.
Keep flying straight at it untill you pass the shields, hit reverse and fire everything you've got as quickly as you can (we're talking 1 or two seconds perhaps), while turning quickly away from the ship so you won't hit it... And then run for it... If you're lucky you may even be able to say goodbye to your opponent with the rear quantums
... One or two attack runs is usually enough to take out the sensor array, allowing you to take you time to finish the enemy off... Even if you just disable the sensors you will have plenty of time to take out the shields and do some serious damage, before they get back up.
Against smaller ships (Akria, Vor'Cha, Borg Sphere), speed again plays a vital factor. Circeling ships is a good strategy, so you can charge your weapons while the enemey fires phasers against you.... Turn your ship when ready, and empty your weapons, and start circeling the other way around it, so your other shields may carge too. No idea in running here, as you will be quite able to take some punishment.
The only thin that can be problematic with this little beauty are bugships, BoP's and equally fast / manuverable ships. They can combat you on mostly the same terms as the Defiant. The Pulse Phasers however are your freind here. For some reason Theese are so incredibble effective agains theese, so in my expirience you can keep the nose facing your enemy for as much time as you can, even thoug you may get a bloddy nose... They will have a cracked skull...
- Good hunting.