Some doctors do not realize how powerful febuxostat is. Why would 250 be such a surprising result on 80mg? That dose is easily sufficient to account for a 50% decrease in the amount of uric acid in the blood.
If your husband is going to take an even stronger dose, make sure the side effects are being carefully monitored. In particular, some doctors seem to be oblivious to liver function test anomalies until the values reach a very high level. And don’t allow the doctors to keep his dose that high after gout symptoms have stopped.
Good luck!