I have experimented for years with various lubes as have most Klismaphiles. In later years, I've explored maximizing insertion pleasure by using just enough lube to get the tip of choice inserted slowly, without discomfort, but increasing pleasure with subtleties of "drag" on the anal tissues which can increase the ecstatic sensations tremendously. My favorite scenario in this department is using a favotite tip, very lightly filmed with vaseline (no prelubing of the anus) for a gasping slow insertion that I repeat several times before turning on my warm water/acidophyllis solution for a heavenly enema.
I would like to hear of others experiences in this area.