I have used this sort of thing in the past and believe that this is a good design practice as well.
I believe from what I have read and seen that opening the DB via the replicaID is faster than opening it via the path, and that would make sense. I create a profile document where I store the replicaIDs of the various DBs that I want to access. This makes maintenance much easier if you ever need to change the RepID and the values are cached so there is no server trip once it is read.
Doing it this way should actually result in some performance improvement. Whether it is a measurable amount I don't know, but maintenance should be easier.