How stable are temperature controlled crystal oscillators?
There are several types of 'regular crystal oscillator'. SC cut is quieter than the more pullable and cheaper AT cut, overtone operation, even at 10MHz, is quieter than fundamental, which has more pulling range.

If you are building a rubidium stabilised clock, then you'd start with an ovened overtone SC crystal. This will be quieter at most frequency offsets than the rubidium or caesium reference. It's only when you get down to mHz offsets, or stability over minutes of operation, that the rubidium reference becomes quiet enough to be worth correcting the crystal.

This timescale implies that a good crystal disciplined from GPS can be every bit as quiet as a rubidium source.