I have been using Chamois Butt'r since late June 2008. I made the switch from Assos immediately after the Cowbell when I branded myself with my chamois. After 12 hours or riding in dry conditions my chamois had cut into my buttocks. The scars are just now fading!
I started using Chamois Butt'r prior to my being sponsored by them. For me, I want to know that a product works before I ask for sponsorship. Nothing worse than to HAVE to use a product that sucks!
After using Chamois Butt'r Eurostyle for 6 months and in all sorts of weather, I must say that this product keeps the 'taint happy. You get the 8oz Eurostyle for $19.99, twice as much as Assos. I use much less due to the thickness and "stay-ability" of the product. I know this because my white saddle is much less polished and people have not asked me why my shorts are oozing a white substance.
My saddle sores have been minimized and I do not have to re-apply during a long training ride or a 12 hour race. And it is made in the good 'ol USA, very important these days.
I have samples, so if you want to give it a try, just ask and you shall receive.