I think for serious subsonic cruise one-upmanship, you'd have to go a long way to beat the old RAF Vulcan B2 and Victor B2, bothof which could cruise at M0.90+ at FL550 or higher.... The RB211 B742 is quite happy at M0.88, and I've seen M0.90 briefly. The VC10, I think, had a high-speed cruise of M0.94, but with all the growths they've sprouted in the military I doubt they can do more than M0.85 now.