So this can get marked as resolved. Everything worked as expected except when you update the nodes the GUI did not show the new version until after we updated the Master. All the issues we had with 1.5.4 were resolved with 1.5.6. Very happy with this update.
GUI is super fast!
The freezing on formating MBR/GPT on start of imaging is back to only a few seconds. Replication seems to be acting normal again.