Is there any truth to what's going around that the G5 diffuser creates more even par up top and that it improves spread? I'm thinking if buying but I don't want to waste coral alimony.
That's literally what the diffuser is meant to do. Even out PAR and spread. There will be a slight reduction in overall PAR.
Also, it's only $23, so not a huge investment (especially in terms of this hobby!)