PRO ! PRO ! PRO !
It will help the server ! And there are other servers that have the same thing, and no one complained about it.
Having vip is a choice, and giving the regular players vip at night i think it's a good idea.
There is another thing about it, if you have it only for a period of time, at some point you will have complains from players for doing it only to reach 1st place ( it's not an uncommon move). I think we should have 3 days per week, something like that. And keep them that way.