For water beading/element protection, the silicone waxes are hard to beat and can go 6 mos at a clip.

For protection against pine stripes and brush rub, rocks and sand abrasion, etc...the silicones don't do much at all.

For proteciton against contact, the Carnuba waxes are better...and if you do it thicker (More coats), you get at least 6 months protection as well.

The Si waxes go on easier/less work, but the wax on/buff off the haze routine for the Carnuba's isn't that big a deal either...but it IS more time consuming.

I found I could put one over the other OK as well, despite the repelliancy of the Si to water and one would have thought, carnuba as well.

So - both ar great, but have strengths and weaknesses.

Oh - and for water spots...that Mr. Clean automotive cleaner stuff actually works!

Use regular old hose water for supply, and this stuff makes it bead off w/o water spots (w/o Mineral deposits)