Finally resolved my issue! 
SteamVR was the issue. I had tried uninstalling and reinstalling it previously but it made no difference.
I finally narrowed it down by running nothing other than SteamVR then starting MSFS. MSFS would get to around 95% loaded then hang. As soon as I quit SteamVR, MSFS would resume and finish loading.
This time to try the SteamVR reinstall, I followed the instructions at the following which seems to have done the trick. Now after reinstalling SteamVR, MSFS loaded up fine and I could get into VR within MSFS without issue. BTW, I was blown away by the impression of VR after only a minute in the Caribou cockpit. Will need to start working through various settings to clean up the image over the weekend but already feel I’m going to be hooked.
The following guide to do the reinstall of SteamVR for anyone else that hits a similar issue: