metal vs. plastic retaining ring for cartridge BB?

In article ,
says...
I am replacing a Shimano UN52 (or UN53?) cartridge bottom bracket,
originally installed in 1997. The left side retaining ring is made of
metal, but the new models, at least what I can easily order in
Switzerland, use plastic. Will the plastic part do the job as well as
the metal one? If not, is there any reason not to re-use the metal
retaining ring from the old BB? Could there be any wear on this part
that would make it fit less closely?
Thanks for your advice.

The plastic retainer works fine. There is also nothing wrong with re-using
your old metal one.
---------------
Alex