I'm on the ZOL fibronics home package for the 20Mb and 90% of the time I'm seeing 10-20Mb, tested to local, American and European servers, only on about three occasions in 15 months have I experienced a constant less than 5Mb speed and it's usually because they're carrying out maintenance. I don't really use it during the day because the home packages are optimised for off peak use and I'm at work anyhow. I have used it during the day previously and I still get good speed, only if you start trying to download stuff it'll step your speed down. I have witnessed this.
At work we're on the same speed package but for business and it's pretty much the same but as it's optimised for peak time it works well.