Just wondering - has anyone actually used the high-safety mode on a production database? Under what server architecture and is there a serious or noticeable performance difference? .. any stats on this?

I'd prefer to use the high-performance mode generally, but 'clever' old microsoft have made this an Enterprise feature and that's not within the budget for our server population.

I note that the TechNet guide says;

"Despite the close coordination between principal and mirror when safety is FULL, database mirroring is not a distributed transaction and does not use a two-phase commit."

... but really isn't that just semantics? The primary still waits for confirmation of the secondary commit ...

As for the debate on DM vs Clustering... I think it's missing the point. Mirroring is a cheap DR solution. It's an intermediate step before the high end hardware replication kit. It's a better DR solution that replication, because it is a full mirror... and yeah it is just a suped-up log shipping. The key advantage is that it's so simple to work with.

Finally, with respect to the login / job / maint plan transfer problem ... how about implementing a DDL trigger? .. Fire off the same code on the mirror server?