> Being able to reboot not just an application but an entire server in seconds in response to an attack is a killer feature of unikernels.

Rebooting an entire server "in seconds" sounds costly here. Maybe if it was more about some secure service being at risk of attack with backup Unikernels, this would make sense. 1-5 unikernels running on high load? The risk of unavailability is greater.

I'd accept this if it were a nanosecond or picosecond reboot. Seconds is too slow.