As of r55615 [1], which has gone live on Wikipedia yesterday, the maximum limit for list=search is 50 results for regular users and 500 for sysops and bots. This is down from 500/5000 because search queries using the maximum limit were causing performance issues.

If you specify srlimit=100 or any number higher than your new maximum limit, you'll get an error message. If you specify srlimit=max , everything will keep working, but you'll get fewer results.

Roan Kattouw (Catrope)