The massive advantage of Pred and Reaper is dewll time ... being there in an area of interest. You really don't need a jet engine for that, fuel consumption.
Now, if you wanted to put together a small squadron of "dash and dump" sorts like the jet model pictured, that's a different role and a different mission. Not a bad thing, of course, but a different mission that need not be a requirement for the armed ISR assets.
Then again, if you want deep strike quickly, why not use ATACMS?
