As long as the alignment is done well and the mesh does not look blobby or muddy the accuracy should not be changing, you are just decreasing the amount of detail. I cannot compare your speed to anything as there are thousands of factors varying. You can move the value of 0.002000 even further to 0.05 I think. It does need a bit of testing really. I cannot speak in general due to your framing thanks to height you shoot from is different your hardware both on site and in machine is different. I recommend you to start heavy on the settings and then move lower on them so you can get quick tests out and see whether you like what you see.