I have purchased 65 Dek Blocks from Lowes in San Diego for my deck project. Prior to starting, we blew out all of the dust and debris from the blocks with a shop vac. Once we began, we found that small stones and particles would crumble off the edges of the blocks , fall under the posts, and change the height every time we made an adjustment.
This has been inconvenient and frustrating at times.
The display Dek Blocks at Lowes seem to be made of a different concrete than the ones that are sold. They are smooth, with sharp edges that do not crumble. The retail Dek Blocks there have poor edges, and are made with a high-content aggregate that crumbles easily. The posts fit, and I'm sure that the blocks meet your load specs.
I like the system- it is very straightforward; however, It is just frustrating to have the added, and unnesessary task of having to deal with the inconsistant quality of these blocks.
Just a heads-up.

Agreed! Quality has degraded past couple years. The problem occurs in processing the concrete. When wet concrete is in the mold it needs to be vibrated to ensure adequate density/porosity is achieved. Another method is to ram a rod repeatedly in the mold to ensure concrete is getting to all the external edges. They may also have changed the grade of sand/rock in the mix. Vibration is the key when concrete is wet in the mold. Looks like someone or some supplier is cutting corners.