Hello Jim,
We met at the SOS in 2008. You asked for references regarding the so-called "NCO Perlring" urban myth. Unfortunately in this case, references often are the problem. Old references could not explain differences in spike base Perlrings such as this, so they made it up as they went along. One of the worst that comes to mind, is that atrocious book Pickelhauben by Eric Johansson, personally responsible for the genocide of countless good helmets as a result of his idiotic advice to soak helmets in water to reshape them and then buff the fittings and coat liberally with lacquer. :angryfire:
The true references in my mind, are period photos. Countless photos show men in the Foot-Troops (Infanterie, Artillerie, etc) who are the rank of Private, wearing what are obviously Eigetumsstück (privately purchased) Pickelhaubes, and clearly visible are any variety of Perlring; plain, round, officer-pattern 'egg & dart' etc. This inability to explain what they did not know, also resulted in some authors making-up that each and every Eigetumsstück Pickelhaube belonged to an Einjährig-Freiwilliger (One year volunteer). Once again, they were wrong; countless photos show men who are not EJF wearing Eigetumsstück helmets.
Any recent reference book worth buying will indicate that men of both Landwehr and Reserve wore the Landwehr Cross on the chest, while for Reserve officer's the Landwehr cross was mounted to the tail feathers, for Landwehr the Landwehr cross was on the chest. A few that come to mind are:
Kraus, J. (2004) The German Army in the First World War Verlag Militaria Vienna
Knötel H. & Pietsch, P. & Collas, Baron D. (1935) Das Deutsches Heer W. Spemann, Stuttgart (1982)
Herr, U, Nguyen, U. (2008) The German Infantry 1871-1914 Two Volumes. Verlag Militaria, Vienna
Kraus, J. (1999) Die feldgraue Uniformierung des deutschen Heeres 1907-1918 .Biblio Verlag, Osnabrück
Reiner, H. (2000) Militaerische Kopfbedeckungen Der Kaiserzeit Motorbuch Verlag, Stuttgart
Das kleine Buch vom Deutschen Heere. (1900) Lipius & Tischer
Pietsch, P.(?) Formations und Uniformierungsgeschichte des Preussen Heeres 1908 bis 1914. Verlag: Helmut Gerhard Schulz, Hamburg (1963)
I am afraid I have zero information on Mannschaften in the Reserve, try Joe's site http://www.pickelhauben.net/ he has quite a few good artuicles on areas such as this.