I know I don't have any credibility here, but I have used several of the SCG products.
I have 2 staples from them - Beyond Black and Dash Away.
The Beyond Black is very easy to apply, and lasts easily 2 weeks, through rain or shine. It is a Semi-Gloss to matte finish, which I like for most applications. It also lasts for a LOOONG time. About 2 sprays will cover most tires. It is a very thin formula so it goes far. It also has never shown any evidence of sling off to me.
The Dash Away is (like someone else said) extremely versatile. I use it on all interior surfaces for a nice fresh clean look (it leaves no evidence of it being used). I also used it this weekend on some carpet stains successfully. And the smell is great.
I use the grime destroyer, and don't plan on changing from it, but can't say there is nothing better for me. It does take you down to the top coat of the vehicle, taking wax etc. with it, so be ready to re-wax after using it.
The wheel cleaner is decent, but again, I am not set on it. I just ordered me some PB Rinse off wheel cleaner from AG yesterday.
The Clearly Better is the only glass cleaner I am currently using. I switched to it from SIG Spray Foam. Like it much better than it.
I have also tried their VooDoo Blend leather rejuv. Not really impressed with it. It is a nice cream that is easy to use, but it does leave leather feeling pretty slick, which most customers (I've had) don't like. Plus, most of the cleaning is accomplished with Dash Away anyhow. I suppose I should wait to try this on some very dried out leather before I am too harsh with it.
Know too that you can order 2L refills on their stuff from their website.
So on what I have tried, the overall consensus is I like it all.
Some of their stuff is staying with me, while I won't mind trying some other stuff on the other products.
DLB