Eh kinda... priority traffic shows the maximum potential speed of your link. The max speed of your link has nothing to do with the speed you'll get on any particular node on the internet. For example if the ISP has too little peering bandwidth to some other speed test.net host you will still be capped by that link.

These days I rarely need large bandwidth to any single host, but have a lot of bandwidth use between many hosts including streaming applications. Bufferbloat is far more apt to be problematic under this workload than ISP priority, unless there is a bandwidth shortage on the local links.