Loc: Sydney, Australia
There are a few synthetic "canes" or as I call them plastic sticks in Carisbrook...
Two which I believe are delrin - I was given one recently by a heavy discipline lover.
I have to say that I don't like them much at all - to me they feel dead in my hand - totally unlike the delicious live feel of a rattan cane in any weight. There isn't the same swish and crack when they're used more a muffled thumping sound that doesn't delight the ear.
As to how painful they are I think it really depends on how the individual processes different sensations. They are certainly a more weighty implement, but I have been reliably informed that the delrin "cane" is not as painful as the Senior Dragon Cane, but more that the sensation is dead thump rather than the lightening crack of an actual cane.
The Sjambok (hippo not plastic) is apparently similar in sensation - though not as long so it doesn't get the same style of stroke.
and yes - I must admit to being a judgmental cane-nerd!