Years ago, Angeles Metals had an ICBO report listing values for plywood shearwalls on metal studs.  I forget the number and will have to look it up.

I have never seen anything for similar diaphragms, and have not noyticed anything in the IBC, although I have not been looking.

Mike McCann
MMC Engineering

I have a copy in a Angeles Metal Systems catalogue of an  ICBO report from June, 1982 for the shearwalls you describe, buy only for 3/8" plywood.  The max allowable load listed, with 3/8" Ply and 1/2" gyp on the other side, is only 300#/ft - rather low.  It is Table V in ICBO report #2392P.  I do not know if it is still current though.  

Angeles Metal Systems was in Los Angeles and the 1980 phone number I have is 213-268-1777.  I believe this was their HQ.

Mike McCann
MMC Engineering

I ran across two other ICBO Reports - ER-5426 from June 1 of 2002 for Stanley fasteners, and ER-5380 from Feb 1, 2003 for Buildex Fasteners.  

They both appear to deal with values for shearwalls and diaphragms.  However, the shear walls appear to be only wind related, whereas the diaphragms were wind and seismic - seemed funny to me.

If you are an ICBO member, you might check with the ICBO for more Evaluation Reports on the subject.

Mike McCann
MMC Engineering

In May, 1993, the American Plywood Association had a Research Report, #154, titled "Structural Panel Shear Walls".  This had ply on metal stud wall values too, nails and staples, single and double sided sheathing.

You might research if the APA has any associated updated publications.

Mike McCann
MMC Engineering

See IBC 2006 - Chapter 22 has some values for steel stud shear walls - pretty good nunbers.