SQL Server database mirroring and primary key

Question

"It is better to use UNIQUEIDENTIFIER type in tables when you use database mirroring" - is it myth?

What may be a reason to use unique primary key for mirroring purpose (single database mirroring case)?

Answer 1

No reason at all.

In mirroring only one database is in-use so there are no collision issues.

Is someone confusing this with replication where several sites are in-use and synch to each other? uniqueidentifier has a use here (and is mandatory in some cases) but still not as clustered index. And you use NOT FOR REPLICATION clauses on triggers and IDENTITY etc