Information on usage

Hello,
generally I work with a microcontroller that can be compiled in C by
its specific compiler(C166 family). With this compiler it is possible
to generate the preprocessed of a file but the output I obtain isn't
so exaustive like gcc does when I do the same job in linux (gcc -E
-dD...). Recently I made a test with gcc including paths of the
C166(so the default headers, instead the linux default libs, are taken
from the microcontroller directory). The result, apart the built-in
defines that gcc insert(these can be easily removed with a script), is
perfect for build a preprocessed header.
My question: is this usage of gcc a valid use? Should I expect some traps?
Consider this not a bug but an help request ...
Thank you,

Claudio