This oscillator can be phase locked to another one. The phase noise will be much lower than any other resonator type oscillator. I have seen a precision frequency reference which used a very stable oscillator which as a by-product had poor phase noise. This noise was removed by using another VCXO in a PLL. The second oscillator had good phase noise but poor stability if used in the ordinary XO mode.
It is common to use a 1 MHz crystal on the 5th overtone to make a 5 MHz source. This gives it 25x bette stability than the same type operating at 5 MHz on the fundamental of the crystal.