After reading this thread a couple weeks ago, I pulled the trigger on Griots Garage Waterless Wash. Had the opportunity to try it out a couple of times and what can I say - it does the job! The two washes I tried - the car wasn't filthy, but did go through a couple of rainy days and is parked outside at home.
The first wash was about five days after I had hand washed and used a spray wax. after the wash, I used a compound, polish & sealant. The one week later was the second GG WW wash.
The key is setting yourself up for success - after washing & a sealant or wax, the waterless wash works much better. If there is no real protective LSP on the surface, the GG WW feels a little grabby.
Using a clean MF towel on each panel helps - if I could see any color on the towel at all, I would flip/rotate. After having wiped down all the surfaces of one panel, I'd use a clean MF to buff it completely dry.
Until further notice I'm a convert unless I see swirls starting to show up. My goal would be to get away from bucket washes entirely, or to save them for the once a year paint correction weekend.
