With regards to subfloors requiremnts; Is is OK to install hardwood (stranded bamboo) over vinyl flooring assuming subfloor under vinyl meets requirments?

What's under the vinyl? What kind of subfloor? Are you nailing, gluing or floating?

Well, making the assumption that your sub-floor system is adequate, there is only one reason why you would have to remove the vinyl.
I have encountered some very tough vinyl floors on occasion that actually deflected the cleats and caused them to scoot along the surface of the sub-floor instead of penetrating them.
So check for that, before commiting to leaving the vinyl in place.
Also, make sure the current floor is not vinyl-asbestos. If so, better to leave it in place and drill and nail the floor by hand.