Looks like the Federation is taking designs from the Klingon's. It also looks like the bridge module is warp capable. Was that intentional? It would be fitting with the design elements; like one large escape pod holding the majority of the senior staff.
From what I understand the bridge on Federation vessels are built separate from the rest of the saucer and can be switched out fairly easily; the same is true for battle-bridges. Adding warp nacelles is logical step up from there. They don't have to be obvious, though - the nacelles could be set on fold-out pylons.