I am loathe to accept that ET has the technology to send a vehicle across light years of space and/or from another dimension, which are capable of incredible acceleration and manoeuvering but seemingly unable to conceal themselves from random people, unless of course we're dealing with the "Burberry clad intergalactic boy-racers" of my previous post.
I might entertain the possibility that our governments are keeping information on such vehicles classified for many reasons - after all, they kept the existence of F117 stealth Fighters secret from the public for a decade.
I am more open to the possibility that our governments (by that I mean the USA, Russia, China and Europe) are testing high performance vehicles which are classified. Remember the SR-71? Take a moment to consider it was designed FIFTY years ago and remained secret for a decade.
Stories from people who have nothing to gain and everything to lose deserve further consideration (ie, Capt Mantell, who lost his life in 1947 when attempting to intercept a UFO), not to mention the reported cases of radiation burns on people who have observed unfamiliar craft at close range. However, I remain open minded...