No, we haven't. You are absolutely right that this would probably mitigate the deadlocks. However,

(1) the deadlocks/WSREP was a problem annoying us, while the query performance was a problem leading to real customer complaints, (2) as I see it right now, we would have needed to take complicated steps to ensure that all application nodes always connect to the same database node; just a hardcoded priority would probably not be enough, (3) a mechanism for (2) would likely make us loose more of the advantages of Galera, e.g. short failover downtimes