Upgrade from XCP-NG 7.6 > 8.0.0 with prefinal .iso went smooth without any problem on a single host. Host system quite old Intel System S5520UR with dual XEON E5645 and 48GB RAM.
Just a quick note: Old Windows XP VM does not boot anymore with XenTools 6.5 or 7.3 installed. When removed in safe mode the VM can be started... On XCP-NG 7.6 this was not the case. VM has booted also with XenTools 6.5.