I've finished the two on the small slab and it is dry fitted to the base, My 1 1/2" Forstner bit is toast. I'll have to make a wood store run before I do the two on the large slab. I was able to move the small slab and fit it to the base by myself, the large one may be a different story. Because of weight and size of the large slab I doubt I will get the slabs pinned today but I should have a functioning workbench within a couple or three days.
Here is the small slab in position and dry fitted to the base:
BTW, I've tried the stability test, push, bump, try to rack, and even with just the small slab dry fitted and no pins, she is solid. This may be a good bench.