C.E. Evans wrote:
The initial problem with the Defiant was that it had trouble with a power plant that would have been better suited on a larger vessel. It took a little bit to resolve that issue,
The cloaking device had trouble hiding the ship due to its power plant's relatively high output, but that wasn't the problem with the ship as far as production goes.
Actually, the problem was
had a power plant that was too big for it.
COMMANDER B.L. SISKO: ...to put it simply, it's overgunned and overpowered for a ship its size. During battle drills, it nearly tore itself apart when the engines were tested at full capacity.
Ultimately, they just found a way to balance things out with its various systems, including the cloaking device.