Just an update for any others who may come looking in the forum for a similar answer.
I could not get a decent buffer bloat score when using the traffic shaper by itself, or with limiters on top.
I can get an A with the limiters by themselves, so I have setup a number of different pipes to have different levels of bandwidth which I can then apply to various vlans. For example IOT devices wont require that much bandwidth so I can throttle those at the VLAN level and use them like pseudo queues.
If you require a specific device routing to a particular pipe you will need to tag it with a firewall rule in the appropriate interface and then match that tag in a floating rule or you will end up with all your pipes getting matched which will see your traffic flitter between the queues. Don't forget to do it for all traffic types, e.g TCP/UDP.
I see this very much as a fudge and to be honest with just one floating rule and multiple clients trying to do a buffer bloat test it does ok at limiting the bandwidth out to the WAN and keeping latency under control, I post the above if you want a smidgin more control.
Of course I may be in the minority with this, and once my new hardware arrive I may try again to get it working a bit better