Mirroring has an processing overhead on the principle server which can, and does, have a performance impact on high TPS servers. I've seen it and discounted this technology for this reason.
Beginning in SQL Server 2008, the principal server compresses the stream of transaction log records before sending it to the mirror server. This log compression occurs in all mirroring sessions.
http://msdn.microsoft.com/en-us/library/ms189852.aspx
Virtually all environments can support and transaction log backup plan which can generally be compressed prior (native or 3rd party) to transporting to a subscriber. Generally they almost always do this anyway. Obviously compressing a log backup has an overhead but this is much smaller than a continual stream to a network connection
I'm not saying mirroring doesn't work. But you are introducing new technology which isn't required and isn't tested on production. This is especially redundant if transaction log backups are already in place.