I rarely run out of RUs before I run out of power on anything. Maybe it would be different with ARM-based blades.
Real hardware, though, vs. cloud, pretty easy case to make for a stable load app.
These aren't blades and I dislike blades for the hardware/vendor lockin reasons you mentioned. Blades usually share power, network, etc. These only share power + baseboard management controller. We can lose a single power supply and still keep on going. We've distributed the applications over multiple chasis, just in case though.