There have also been some cute measurements by K. Kern's group some years ago. I attended a talk of his at the time but guess that this must have been published in the meantime.
Observation of shell effects in superconducting nanoparticles of Sn (DOI: 10.1038/NMAT2768)
Experimental observation of thermal fluctuations in single superconducting Pb nanoparticles through tunneling measurements (DOI: 10.1103/PhysRevB.84.104525 & DOI: 10.1103/PhysRevB.84.219906)
In the superconducting state you have an ideal diamagnet below T_{C1} and below H_C. Then M=-H_appl.
Otherwise something such as a saturation magnetization does not exist (it is not a ferromagnet). According to O'Handley ("Modern magnetic materials", Wiley, 2000), Fig. 3.4 on page 69 Pb is a diamagnet with an atomic susceptibility of about -3x10^-5 (atomic units). Please check the literature for proper definitions.