Uds are over rated. Orc clerics with high gains and avians too are far superior
Ambush is the way to go. You start to see the difference mid age trending towards late age.
Inability to retrain is just harsh.
The counter would be to use WS but in that case if you were chained and used ws then you would have no incoming to save you.
UD are good for mid 50's. I doubt you will find more than 2 top 10 kingdoms eoa running ud strat.