Remember that if you ever want to install windows with bootcamp in the fusion drive you won't be able to use the ssd portion so the system will run only in the hdd. You probably get less nois with fusion drive than ssd+external hdd but now with thunderbolt 3 external ssd is going to be an easy option (and in 1-2 years even 2tb ssd won't cost much).
Noted. I will not be running bootcamp but only VMs.