AESTHETICALLY, I LIKE THE LOOKS OF THIS SHIP VERY MUCH.  (click here to see the FASA original.) Like so many Klingon ships, it has the warp nacelles mounted on the wings, a long neck, and the traditional Klingon command pod.  This ship is even featured in the cutaway color painting on the cover of the Klingon Ship Recognition Manual, which is pretty surprising considering that the D-7 cruiser is far more recognizable to fans.
        In game play, the D-20 is frustrating if only because none of the three official versions mount any torpedo weaponry!  Sans the punch of torpedoes, this ship is only good when used in numbers, or head-to-head against other ships also lacking torpedoes.  Thus, when I did my re-draw in 2007, I decided to give the class a new model, in addition to a refreshed look, with a single torpedo mounted in the forward arc.  I think a torp gives this class much greater versatility in game play, and makes it a lot more fun.
        I hope the new look also works for fans and gamers.  I tried to stick to the FASA schematic as much as possible, mostly because there was nothing terribly amiss with the original, save for component scalar problems.  Like the D-9, my D-20 has a larger command pod than originally shown on the FASA version, if only so that the command pod—the one item that is most ubiquitous within the Klingon fleet—remains to scale with that of the D-7 K'tinga.

   — BRT

From the FASA Star Trek KLINGON SHIP RECOGNITION MANUAL, circa 1985
D-20 (Death Rite) Class VII Cruiser
Known Sphere Of Operation: Empire-wide use
Data Reliability: C
Major Data Source: Klingon Sector Intelligence
The D-20 was commissioned on Stardate 1/9606 and immediately rushed into the Four Years War, where they were used much like the famed D-7. Though the class suffered from lack of maneuver power and a relatively weak superstructure, it seemed to make up-for these deficiencies in its weapons, and shielding. Mounting the KWC-1 engines, the D-20A was able to attain higher warp speeds than the D-7, but was less maneuverable. Eighty-six have been converted to the D-20C.
        This fault was corrected with the introduction of the D- 20C on Stardate2/1202. This model is far more maneuverable and has more power, as well as a more efficient shielding system and stronger superstructure. Because of its extra power, KD-6 disruptors were added, increasing firepower by 50%. This model is still in production even though the D-20D has entered service on Stardate 2/1701, mounting KD-8 disruptors, which deliver 16% more destructive power over a greater distance.
        Of the 634 D-20s built, 224 Cs and 80 Ds remain in active service; 292 As, 19 Cs, and 1 D have been destroyed; 2 As, 4 Cs, and 1 D are listed as missing; 1 C and 1 D have been scrapped; and 2 As, 28 Cs, and 4 Ds are in the service of ranking and prominent families of the Empire. The class is being produced at Gnuu Re' and at H'rez. These facilities were originally set up to refit A models to C models, but when orders were issued for the production of the D model, Imperial Command redesignated both bases as production facilities. They began producing new ships as soon as the last of the older models had been refit. Both facilities combined produce a total of 13 ships per year.
        The class is named from "the death of honor", a traditional death rite involving a silver dagger. In this rite, a captive who has fought well is killed with a silver dagger handed down through the family lines. When a family line is broken, the dagger is destroyed after it has been used to eliminate the last family member.