limit_req_zone values (no replies)

Greetings,

I have the limit_req_zone working great in testing environment with the following values

limit_req_zone $server_name zone=perserver:10m rate=5r/s;
limit_req zone=perserver burst=5;

The site has up to 750 simultaneous users at peak times.

What values are suitable for such traffic levels ?, what are values are people using with similar traffic levels ?

Cheers,

Tom.