Well, the first update to Blender 2.80 has been released - Blender 2.81. Here
The version I downloaded 2 days ago did not include the latest .babylon exporter which is available here . Open the new version of Blender ->Edit-> Preferences ->Addons -> then find the .zip file you downloaded ( Blender2Babylon-6.2.zip) and click Install. This will give you the 6.2.3 version of @JCPalmer 's great addon.
I also had to activate my GPU for faster texture baking etc.
cheers, gryff 
Yeah, I saw that on twitter. Scrolled through the features & noticed the nVidia driver thing. Did not get 2.81 yet.
When the exporter does the baking for you, I sped that up about 10x, by setting the scene.render.tile_x & tile_y equal to the bake dimensions so that there is only one tile. Takes more gpu memory, but it kills. I also dropped the scene.cycles.samples down to only 16.
I also just noticed that I am storing the scene.render.use_pass_indirect & use_pass_direct,then setting them both to False. At the end, I am resetting them both, but not with the stored values, but 'False` again. Going to need to look at that again. I got all this from Blendstack, but did not put the url in the code.