Same here.
I'm using the nasal pillows and have the same issues. My airflow is exactly the same as in my at home unit, and I've also tried with and without the HumidX inserts without any difference. The issue resolves immediately as soon as I return home and go back to my at home unit - also with nasal pillows.
I have exactly the same issue, and I've had it since the first time I used the Resmed AirMini. It happens every time I use it and I have to use Claritin and Flonase the entire time I'm traveling. The sneezing it awful because it comes in waves of 8-15 sneezes at a time. As soon as I stop using the machine and resume with my at home unit, the sneezing stops. Has anyone found a reasonable solution?