Having seen someone raise concerns about their 300Mbps VM service providing only 160Mbps I thought I'd share my recent experience.
I recently had cause to turn on parental control on my Asus RT-AC66U due to a misbehaving teen. To enable parental control this particular router needs to disable NAT acceleration. Lo and behold, disabling NAT acceleration limits the throughput to around 160Mbps because its CPU, which is now having to do more, is not powerful enough to go faster. This limit affects both single and multiple stream throughput.
So I'd suggest this is another thing that needs to be considered alongside wireless as a possible cause of poor test results. Of course we all know VM have issues in some areas but sometimes it isn't all their fault.