Should bootstrap-O3 be the default for building/testing GCC?

[Gary Funck]

Currently, the default optimization level when building,
bootstrapping GCC is -O2.

We routinely build with --with-build-config='bootstrap-debug bootstrap-O3'
because we want to verify that our UPC changes don't affect the
compiler when built with full optimizations.  We also build
with --enable-checking=all.

Since most developers probably build/test GCC with the default -O2 options,
we fairly often run into -O3 related issues when building GCC.
Enough so that we're considering just using the default -O2 settings.

I'm wondering if there might be benefit in changing the current defaults
to use -O3 instead?  Or perhaps have the configure infrastructure
determine that the build is for a development version of GCC
and set the flags and options accordingly?

Somewhat related: has anyone recently determined whether a GCC built
with -O3 is generally faster/smaller than one built at -O2?

thanks,
- Gary