Blackstone folks individually write the reports for sure. When I was racing regularly, I would send them an oil sample after every race, as well as a separate sample from my vented catch can. The first time I did this, I got a huge report back regarding the catch can sample and were really interested in continuing as there has basically been zero research on what you SHOULD see in a catch can (in terms of ratios of water, elements, etc).
Every time, individual reports which not just address the current sample, but they also do the analysis against a previous sample (for the same engine) so you can get some trend data on how things are going.
If you're using any of these services for a one-off measurement, save your money. It only provides a single data point... and a single point does not allow for you to make real trend data. That said, if you see a lot of bearing-type materials in a single sample, you know things are in rough shape.
Your mileage may vary