The Avenger class ship was a extremely successful class being the most advanced class of her time surpassing even the Sovereign with regards to firepower and technology. Being the first Federation starship equipped with Romulan cloaking device.
Due to her success as a typical starship saucer/engineering sections several of the class were refit. The refit turned out to be a complete overhaul and rebuild into a new class - the Asserter Class. This new class featured advanced phaser arrays and phase cannons as well as 2 kinds of torpedoes - photon and quantum. It also featured a separate rotating gunnery bridge on the underside and 2 "Captain's Yachts" similar to the Galaxy Class one. The torpedo launchers were placed above the nacelle struts and the top phaser arrays where placed underneath the bridge in a circle, while the underside ones where underneath the gunnery control bridge. this formation allowed the "Asserter" class to fire in virtually any direction without being inhibited by the engineering deck.
Anyhow enough said, I know that the base is pretty much the same as my Avenger but please still...