If you've ever sat on a real JBL you would completely understand the attraction. First off, the warm cushion feels very nice nd the ball shaped valve assembly completely plugs your anal area, making retention of the water easy and comfortable. The water simply cannot come out. The more you relax your anus, the better the seal.
The original nozzles, both adult and child, have a large number of tiny hole. There is no "jetting" of the solution, It just sort of oozes into you, gently flooding your colon. In fact, I can't usually even feel the water flow. This doesn't provoke any urge to evacuate hence there is no cramping or urge to poo.
The bag holds about five quart and if you just relax and sit, most all of that goes into your colon, filling it gently and completely from end to end. If a person usually gets full to bursting with a 2 quart bag enema, you will be astounded at how easily the JBL gets in a much larger enema. Also, the slow inflow and resulting increased retention time softens the poo a lot.
When the urge does finally come, one has only to close the spigot, stand up, lift the seat cover, sit and poo. You will think Niagra Falls has be rerouted through your butt. One complete sitting and you're totally empty.
In my opinion, a session sitting on a JBL is a wonderful, cleansing, effortless, sensuous experience.