PD7, the Primero has been used by a large variety of other watch brands, some more distinguished than others. A few years ago, a bunch of us came up with a list:

Boucheron - in white gold, with cal 400Z branded "Boucheron El Primero" on rotor
Concord - ( ? - 2002) Impresario - cal. 411 (without moonphase)
Dior Chiffre Rouge
DuBois & Fils - Zenith cal 410 in model "Montre 1812"
Dunhill - cal. 410
Ebel - Calibre 134 (approx 1984-1994?)
Ekegren Genève - 3019 PHF
Louis Vuitton - Tambour LV277
Movado - Datron HS 360 (1969 - 1974)
Panerai - Calibre OP IV (2000-2003) in PAM 72
Parmigiani -
Rolex - Rolex 4030 (1984 - 2000) for Rolex Cosmograph Daytona (cal. 400 slowed down to 28000VPH and without date)
Daniel Roth -
Kurth Schaffo ("Chrono d'Oro")
TAGHeuer - Calibre 36 ( ? - present), in Grand Carrera, Link, Monza
Tourneau - yellow gold - cal. 3019 PHF
Ulysse Nardin (UN cal. 10 based on cal. 400), 50 pieces in yellow gold, made in 1980's
Urban Jurgenssen Copenhagen (3019 PHF)
Van Ree Watches - DNA watch (El Primero 400)
Waldan International - (current, uses vintage movements purchased in 1980) Astronic Chronograph

whether any of these are regarded as collectible is up to the individual. My interest extends to the Movado versions as they are contemporaneous with the originals. There is rationale for including a few of the others as historically important (e.g. Waldan, Ebel), and of course TAGHeuer enthusiasts are delighted to see the brand use a world class engine, particularly this year, as TAGHeuer has introduced Primero-powered Carreras. I can say that there is no terribly well developed market or community for any of the modern (post 1984) applications of Primero, the dumbed-down Rolex version excepted.