Speaking of gcc and arm, some archs use -Os by default, but arm is using only -O. Some arm targets (e.g. AMS C200v2) with very little ram could benefit quite a bit from using -Os and so far it's working fine for me with rockbox gcc 4.0.3, so I would propose making -Os default for at least the AMS low memory arm targets.
-- Tobias PGP: http://8ef7ddba.uguu.de