but if 2.0mm fits, then why not have it at that thickness on both ends?
most hubs I've seen fit 2.34mm more snugly, but otherwise no problem.
I've heard that the benefit of 1.8mm spokes is that the spoke nipples have more material due to the smaller tapped hole down the middle. 2mm at the hub still allows for a reasonably snug fit there and 1.5mm in the middle yields a lightweight spoke.
Honestly, if I had seen these available when building my last set of wheels I likely would have used them.