Originally I used it at 6:1, now I use 10:1...I still have a bottle of it mixed up, it's a good cheap solution that works. It's not as sexy as some other products, and I don't really like the smell (although there are plenty of products that I don't really like the smell of).
I'm not a pro, I'm presuming for a pro that a diluted APC is going to be more effective at broad-spectrum cleaning for the soils you would encounter. I think most forum members on their own car which is better cared for use something like Meg's QID or one of the similar products.
We're bombarded here on the forums by a huge number of products, with new and improved ones (and even step-changes in technology) all the time. So many of them serve the same function, and it's easy to get buried in the hype, if not just the mound of choices.
Thanks for the reminder that there are some simple, cheap, locally available products that work, like in the other recent thread where a member was successful using Folex.