I propose to make same limits (500 on slow and 5000 on fast queries) to
all users for all actions (maybe expect content requests). Reasons:
1. It would be less expensive to fetch 500 (5000) rows on *one query*
than to do *10 times the same query.
2. Usually it's very hard to determine if you may use extended limits
(for now it's group "sysop" (you won't beleive me, but may not exist on
wiki) or "bot" right). I propose to at least add new user right called
"apihighlimits". Anyway, it cause user to do extra query.