I strive to synchronize my tefila with the tzibur on Shema and the beginning of Shmoneh Esra.
However, I daven quite slowly (metoch nesyon kavana) and I am almost always somewhere in the middle when the shatz is hitting kedusha.
This seems problematic to me. I have not been able to find specific reference to slow daveners in the Mishna Brura.
I am aware of the halacha that if you join Shmoneh Esra late - you say the berachot be'kol together with the shatz.
This is a different case - where one starts with the kahal and falls behind and must remain silent.