Souverän M1000 was introduced in 1997. Consumers had expressed a desire for prestigious but not ostentatious fountain pens (Pelikan Schreibgeräte). M1000 was the largest or "oversized" of Pelikan's fountain pens. It was probably designed to compete with the similarly sized Montblanc Meisterstück 149⁽¹⁾. But, when you actually write with it, you realize that M1000 is not simply a fountain pen that is a larger version of M800, and you also realize that the nib characteristics are different between M1000 and 149, even for the same oversized fountain pen. According to Pelikan’s Perch, "the nib is very springy and will require a softer touch than some of the other, stiffer modern nibs seen today. It puts down a very generous and wet line of ink". M1000 is larger than other Pelikans, so most people will probably write with the pen lying down rather than standing up⁽²⁾. As a result, writing pressure is reduced. The structure of the nib has been designed to be softer than its smaller counterparts. As a result, the nib flexes more with less pressure and produces more ink flow (called "wet nib") to accommodate this writing style. Note that the character width tends to be thicker due to the writing style of holding the pen flat and the wet nib. According to Pelikan-collectibles, M1000 "is often designated as a signature pen." This is probably because the wet nib prevents the letters from being grazed even when the signature is written quickly and with less pressure. The nib of M1000 makes it easy to change the character width in response to writing pressure, which may also be the reason for it. Interestingly, the ink capacity is 1.35 ml, the same as M800. Is this because increasing the ink capacity further would make the ink more likely to drip?​

In 2003, the specifications were changed: there is only one chick left in the nest and nib (Pelikan-collectibles.com). 

Note;⁽¹⁾"...the history of Pelikan had been a history of small, light pens. Even as the company’s rivals, most notably Montblanc and Osmia, moved toward larger pens as early as the 1930s, Pelikan remained with its core size, ranging from the diminutive 4 3/4 inches of the 100 to a maximum of 5 1/4 inches for the slender 400NN. The 800, with a smooth brass filling mechanism, was neither small nor light and was, presumably, meant to go up against the larger contemporary Montblanc149. ... A decade later Pelikan again took on the legendary Montblanc 149 with an even larger pen the M1000..." (Pelikan Pens: History).
⁽²⁾This would be even more so with M1050, which had a heavy cap.