I would guess that you could get some tailoring by changing pressure, but the Coanda effect really counts on boundary layer attachment and then separation to do its thing, so there are almost certainly limits. Turns out the RSRA never flew through a transition so the excitement around the hangar was speculative. Some helpful reference material on the technology.

http://www.sikorskyarchives.com/X-WING.php

https://en.m.wikipedia.org/wiki/Blown_flap

Also, some NASA concepts for personal electric VTOL:

http://ntrs.nasa.gov/archive/nasa/ca...0110011311.pdf

https://m.youtube.com/watch?v=I_KloqLa2Og