From what I can see, Digiweb's quota system for the downlink does not seem too bad, as it is still possible to make use of the quota. However, I think the main reason they do this is to avoid network surges at the start and end of each month, such as when one tries using up the remaining quota on the last days of the month or where one has been building a list of files to download once the new month starts. On the other hand, this issue use to only really be noticed on satellite based Internet, where the performance was quite good in the middle of the month, but terrible at the beginning and end of the month.
On the other hand, they have quite a nasty surprise for those who do exceed their quota
going by their FAQ. For example, they mention that if one exceeds the 10GB limit by 2GB before the speed restriction is put in place, the restriction is only removed once they fall below the quota by what they exceeded by, i.e. below 8GB (10GB - 2GB). This effectively means that if one ended up going 10GB over their 40GB limit before their speed was cut, they would need to wait until they fall below 30GB over the 30-day rolling period before the restriction is removed.
I must find out what their upload quota is, as my uplink has been cut to about 64k a few days ago (use to run at ~310K), despite being on their Xtra (3Mb/384K) package
According to the My Traffic report, I've used 3.89GB on the uplink over the past 30 days and 8.93GB on the downlink, so I definitely haven't exceeded my 40GB allowance, even if adding both. Going by the last couple of IrishISPTest's, I get ~2.3Mbps to 2.4Mbps down and just ~62kbps up. I am fairly heavy uploader due to making regular VPN and FTP connections to transfer files, so would be rather disappointed to find out that they only allow somewhere between 3GB and 4GB upload allowance on their DSL Xtra package.
Edit: My mistake about the uplink restriction: My D-link gaming router has a traffic shapping feature, which got enabled after a recent firmware update. Apparently, this feature is designed to limit the uplink to prevent any upload from hogging the bandwidth and minimising latency when setting up new connections. While this may be useful to allow fast browsing of the Internet and games playing while FTPing up files, having uploads slowed down to around 8KB/s is not useful if there is a lot of content being uploaded. However, while Once this feature was disabled, my uplink went up to ~260Kbps after a handful of speed tests on this site.