I've worked as a software developer for over 10 years too and "suits jumping the gun" is what this update seems to me too. And it's too bad because I'm also a professional musician (two degrees in music and all) and I'm doubly pissed at this update.
That's the one thing the update warns you about. As I connected my 1.9 to workbench HD I got an error message saying that I needed 2.0.
But yes, I tried all 4 combinations in 3 different systems to no avail (1.9 -> workbench, 1.9 workbench HD, 2.0 -> workbench, and finally 2.0 -> workbench HD) in OSX 10.8, Windows 7 (as a VM in OSX), and Windows 7 on a dedicated host.
As I said earlier, going back to 1.9 worked in every case so I'm positive other pieces of the chain are working fine. I'll just wait until 2.0.1 is out or maybe an updated version of workbench HD.