This is great news, of course, but it should be mentioned that the FT-243 crystals sold previously were actually HC-49/U crystals in FT-243 shells. This can be an issue, particularly for vacuum tube oscillators that put more current through the crystals than the smaller HC-49/U architecture can handle.
True. For example they don't do well in a simple transmitter like an AC-1 with a single stage 6V6/6L6, where they tend to chirp a LOT. I've never managed to cook one, but high crystal currents are problematic. However, I've used them without any problems in other rigs with a low level crystal oscillator — DX-20, Globe Scout, Ranger, Valiant, Globe Champ, Globe King, and others. And in those cases, they work just fine.
