Thanks for posting! I typically just set the "traffic-shape rate" to guaranteed upload rate given by the provider. However, I always verify the upload speed prior to setting the command by using a few speed test services. If more accurate or customized bandwidth tests are needed, you can use applications such as "iperf".
The bandwidth setting, within the interface, does not affect QoS. However, it does allow for a specified interface bandwidth to be made available for other processes, such as routing protocols.