Cheers jonny/Nuckin, my temps were definitely not as low as I liked, especially the NB consistently reaching 50c.
I did temporarily put an 80mm pointing directly at the Fusion Block and that actually reduced temps by 10c, so I would imagine using the Thermalright would probably reduce temps by 15-16c in total.
SB is around 42-43c on average without any extra fans, so yeah, sounds like the Thermalright will be a great idea.