RT render farm

Hi guys i hope this is the write place to post this.

I have Vray for 3dsmax and Maya along with 5 render node licenses.

i currenlty have total of 7 nodes 2x workstations and 5x render blades.

I am looking to switch to full GPU/CPU solution what vray supports now. Question is should i upgrade my existing rig with dual 1080 gpus ? (is DR uspported in that config?)
or should i build a new single renderblade with 8 x gpu’s I think thats the limit if i am not wrong. In that case my old rig gets almost useless. I do hope to utilise my render blades.

Please let me know. typically i get print jobs 10K renders but time and again i get into motion vfx as well. What are your suggestions as of now can afford either one.