Many people are confused about the 10 MHz reference lock input on the IC-9700. And so was I. While all of us expected the VCXO was locked to the 10 MHz input (which in most cases will be locked to a GPSDO) it isn’t. Unlike the new IC-7610, which is locked, the 10 MHz input on the IC-9700 can only be used to calibrate the transceivers’ VCXO. And even this doesn’t seem to be most accurate.
According Rex (VK7MO) tests, he had a 4 Hz error on 144 MHz, a 40 Hz error on 1296 MHz. Icom has work to do to fix this (and the ALC / Power Overshoot) error. A fix could be a (more) permanent lock/sync, but a fix could also be made in the fan controller, since the temperature is directly involved with the IC-9700’s drift.
People using the IC-9700 for FM (repeaters), satellite, FT8, etc. should not worry. People using the IC-9700 for weak-signal modes and EME should, and not putting the old locked IC-910(0) or TS-2000 on sale, yet.