I was one of the first to get BlackFire, and I offered to apply it to my wife's friend's Mercedes E420 (2000 or 2001). The car is primarily a garage queen...when I detailed it, it had 2,335 miles and it's always garaged. She doesn't work, and only drives when running errands, etc. (They have 7 cars between the two of them)
So, I applied the BF after claying and washing with Dawn twice (wash, clay, wash). Since the paint was in great condition, I didn't use any 3M products beforehand. I applied 1 coat of the polish and 3 coats of the sealant, using my PC and CMA pads.
At first, I was really impressed with it because it looked great and was so easy to use. I thought it was going to be my new favorite product.
I did the initial detail about a week before Thanksgiving. She drove it home, and then came back for a wash about three weeks later (2,412 miles). I was shocked at how unslick the car was before the wash, and even more shocked by how the wash didn't seem to improve it at all. I QD'd it and sent her back home.
She came back today for a second wash (2,501 miles) and it's like I never even waxed it. The surface isn't slick at all, but it is still somewhat glossy. I did a side-by-side with my BMW (similar colors) which had been P21S'd around the second week of December, and I swear the BMW was more slick.
She swears she hasn't been through any carwashes, nor has her husband washed the car inbetween. Another thing I noticed that turned me off a bit was that the black trim pieces seemed to "dry out" with the BF wash, unlike when washing with Zaino Z7 which seems to give a bonus "dressing" of the trim.
It might be the Mercedes paint, but my initial impressions have faded quickly (unfortunately, because it was so easy to apply and use). I'll follow up later, after another wash.