I'm mainly using Cubase and only rearly do something with Logic.
What I can say from my own experience:
- Good USB hubs with MTT help. I got myself two Exsys EX-1188-HMS USB 3.0 industry grade hubs to connect all my music gear. Very few USB releated problems with these. Most likely you should als be fine with the Elektron Overhub.
- Ever sInce upgrading to MacOS Mojave (10.14.6), the Virus TI runs much more stable compared to Sierra / High Sierra, but I guess your iMac is not suppoerted anymore by newer OS.
- Random bursts of noise which require the Virus to be restarted are most probably related to one or both of the DSP crashing, which could indicated a hardware problem
- The arpeggiator was not designed to be used from within a DAW (Arp as Step Sequencer Glitch?), and often gets out of sync, also with other setups. I gave up on using it in the context of a DAW.
Maybe some of that helps.