211 EHD not compatible with 722

[steve4810]

Back on 06/06 KAB said:

Last I read, the 211 EHD would not be compatible with the 622/722. Don't know for sure, however.

and though I asked where he heard that I got no response.

Has anyone else heard this rumor?

If you have could you share who said it or where you heard it?

Inquiring minds want to know.