I did the same awhile ago. Had an existing single E5-1650 server for Plex and added BI to it. I got chided soundly when asking here about my server for not having hardware encoding capabilities. My machine runs at about 13%
Blue Iris CPU utilization without Quicksync for (8) 2MP IP cameras. Doesn't appear that BI is much of a memory hog, but you have PLENTY so no issues there.
I haven't had any desire to add a dedicated BI server right now. One caveat is that my media server is for LOCAL hosting only, as I don't have "friends and family" that login remotely to stream my media. Generally this means I have no more than 2-3 streams of media while the machine is also handling the (8) IP cameras. I will check CPU utilization when this is happening and report back.
You aren't out that much time trying it out. I think you can export your settings from your existing BI install, install BI on the media server, import your settings, and watch your CPU utilization.