This is correct in British English as far as I know however I would favour an alternative structure such as:
She is an excellent student, as is he.
They are excellent students, as are we.
They problem is that the meaning might slightly change with this alteration. The original sentences convey the meaning that 'A is <em>just</em> as good as B' as if someone has suggested otherwise. My 'correction' has the meaning that 'A+B are good' as if to clarify that everyone, in fact, is good.
n.b. this is fairly high level analysis so I wouldn't worry too much, your similie is correct.
Nono, sorry, there is not any particle there, it's just She is as excellent student as he is.
But She is an excellent student, just as he is is more natural.
Comparatives
She is as an excellent A STUDENT as he is.
They are as excellent STUDENTS as we are.
The structures are correct, only the particle is before the adjective.
Another way to say it could be "She is an excellent student, just as he is." ;)
