They have been known to crash during a download.
(posted on here a few times by other users)

In this circumstance, your car WILL have to be towed to a FORD dealer
for an ecu reprogram which if your car is under waranty, will void it.

In the cases I have seen, the makers wont/cant help you !
(Although I may be wrong)

As for power figures/buying one, I suggest calling ROB @ SCC

http://www.scc.superchips.co.uk/