The two important points for making a good sabayon are: a pinch of flour (for easier blending) and a bain-marie (gradual rise in temperature).
Syllabub is often poured over a dessert, but you can also serve it plain in a small cup (warmed beforehand) instead of coffee or tea.
Syllabub is best served warm, on something which should be neither too hot ( not straight from the oven), nor too cold (not straight from the fridge).
This recipe is for a sweet syllabub but it can also be made savoury (see above). You will notice that in this case, because of the absence of sugar, the syllabub thickens much more quickly.