Great customer support from my experiance, my local representative was very helpful. I have read good things about their products, but I have only used their oil analysis kit for a different vehicle. I might upgrade to amsoil when I do my next oil change. I'm running some cheap synthetic through now to clean it out and check for leaks.
Also, if you intend on buying a lot of their products, you can get a prefered membership that pays for itself after about $100 worth of products. its $20 if I remember right, and you get dealer pricing.
I was looking at this when I was thinking of switching my truck to synthetic... $150 for oil, or $20 membership and $110 for oil... This would also be worth it if you wanted to do multiple cars or had a few friends that wanted to go sythetic as well.