And I reply:
You appear to be asking 2 different questions in your second bullet.
Not that you can execute them, but you can verify your understanding of the system.
There are of course multiple levels of scenarios. I think you can start with the less powerful scenarios as features come on line and if you have time also execute parts of the powerful scenarios.
However, as Marick indicates in his paper, New Models for Test Development, you have to balance the effort needed of partially executing scenarios – do you need stubs & drivers or other simulators to do it.