> I really think it's difficult to see the two as being anywhere near the same league.

I really don't understand why it's difficult to you. 55 flights aren't a success by chance. What you've said about staggering achievement fully applies to Tu-144. The creators were facing same challenges, and had to solve them in the same time - and got the plane flyable, if not efficient and safe enough, to be used by NASA in 2000-s.

We can say that Concorde had less technical flaws than Tu-144, clear in hindsight, but I don't see how that makes them incomparable.