Did a few more tests. It appears the reason this work around generates smaller obj files is because it strips the UV data from the file, which is no big deal really. I've only done 4 or 5 tests so far all using the same model but when "Import UV's..." in UVMapper Pro was used to reapply the UV's from the original model then the file size reverted to the exact same as the original. So, there's no free lunch on file size but it looks like the work around is pretty sound.