I am working live a lot with synced delays, the Gilmour / The Edge kind of things, but also for slicer effects for some metal stuff. I find the syncing quite stable - but you have to remind: It's only clock syncing, that means that the tempo of the clock input and the tempo for the delays (or tremolo steps) are the same - but that does not mean that both run in the same phase: E.g. if you have set up an echo with quarter notes, they will have the correct ms of delay and even follow tempo changes, but they do not automatically match the beat of your song. You have to ensure additionally, that the delay starts more or less exactly with the beat. From my experience, the most reliable way is to call up the preset on the first beat of a bar, so I step on the preset footswitch in the right moment and all is fine. I am not sure if activating the delay in an already called up preset is doing the same thing. In a studio context, my suggestion would be to include a MIDI program change in a Cubase track to call up the POD preset (and with this start the delay / pattern tremolo etc.) and move this event slightly forward or behind to match the beat of your song exactly.