Benke and Medgyes (2006) examined learner perceptions in the differences between NESTs and non-NESTs. Their findings showed that these two teacher groups adopt distinctly different teaching attitudes and teaching methods. Compared with NESTs, non-NESTs have a more structured approach to teaching grammar and are good at addressing grammatical difficulties. Because of their familiarity with the local educational environment, they provide more exam preparation, supply the L1 equivalent of certain English words, and develop translation skills. However, the non-NESTs tend to use too much L1 in the classroom. Their poor pronunciation and outdated language are often criticized. However, NESTs are ideal models to imitate and are better able to elicit their learners to speak aloud. Learners stated that NESTs are friendlier, and that their lessons are lively and colorful. However, lower-level learners had difficulty understanding their NESTs. Without a shared L1, NESTs tend to leave problems unexplained. A communication gap between NESTs and their learners often occurs because of their different language and cultural backgrounds.
Medgyes (1992) also attempts to differentiate between native speakers (NSs) and non-native speakers (NNSs), arguing that “non-native speakers can never achieve a native speaker’s competence” because they “can never be as creative and original as those whom they have learnt to copy” (pp. 342- 343). Similarly, Cook (1999) asserts that only a small percentage of second language (L2) users may pass for native speakers, comparing the feat with becoming an Olympian athlete or an opera singer. However, the sheer number of highly articulate expert non-native speakers in the ELT profession and in the academic field of applied linguistics refutes this notion. We contend that once an L2 learner reaches what Cook (1999) calls the “final” stage of language acquisition (which Cook notes is very difficult to define), the difference between native competence and advanced non-native competence is negligible.
http://www.tesl-ej.org/wordpress/issues/volume16/ej63/ej63a1/