Here is what I did in order ...
Hit patch, waited and was told to patch again.
Hit patch a 2nd time but quit patcher before finishing.
Uninstalled and deleted all MWO files and did a clean reinstall.
Was told to patch again, but instead ran the repair tool (which fixed numerous errors).
At this point everything is working fine. In fact, since switching to 64-bit client and DX11, I am getting noticeably better performance than before. So keeping my fingers crossed that all stays in working order from here on out.