Has anyone ever used one?  I fish a small and shallow river 1/2 the year and am frequently having to navigate shallow water.  This sounds like it would really help make sure the skeg and prop didn't dig down into the sand and ruin the motor.  If anyone owns one let me know how it works.  

I use one on an old evinrude 15hp.  My issue isn't sand as much as keeping the prop from the rocks where I fish.

I haven't had any problems with it at all and in two years I only have a very small paint chip off the prop.

I have heard they can severely decrease the performance of your motor, decreasing your top speed by several mph if not more.   I looked into this same producut for my boat and it appears it would work very well.  However i settled for a normal skeg guard due to possiblity of performance issues with that one.  Look at Cableas site under this product, there are several reviews there as well.