You can only cut so many corners and hope to have success at something as difficult as landing on Mars. While I hope the Beagle 2 team is successful, I can't help but have my doubts. Sometimes, it's the most trivial things that come back to bite you, such as Lockheed-Martin's screwup on the English-Metric conversions on Mars Polar Lander (and JPL's failure to catch the mistake). Even though the error caused a misaimed trajectory on the order of 1 part per million, that was enough to cause mission failure and a lot of embarrassment. Sometimes, having another team performing a sanity check on your work is money well spent.

As for your remarks on the SR-71 development team, Ben Rich wrote in his book "Shunk Works" that someone once said of Kelly Johnson that the "son of a bitch could SEE air!" Johnson thought that was one of the nicest things anyone ever said about him. By all accounts, he was a crusty old bastard to work for who would on occasion literally kick people in the ass, but he was also perhaps the greatest aeronautical engineer and project manager who ever lived. To me, Burt Rutan is probably a close second.