Last week I came up with this option. I haven't made performace tests. Maybe you could help me with that.

DECLARE @test-2TABLE(

myintint)

INSERT INTO @test-2 VALUES(1),(2),(3),(4),(5),(6),(7),(8),(9);

WITH CTE AS(

SELECT myint,

NTILE( 2) OVER( ORDER BY myint) tile

FROM @test-2

)

SELECT CASE WHEN SUM( CASE WHEN tile = 1 THEN 1 END) = SUM( CASE WHEN tile = 2 THEN 1 END)

THEN (MAX( CASE WHEN tile = 1 THEN myint END) + MIN( CASE WHEN tile = 2 THEN myint END))/2.0

ELSE MAX( CASE WHEN tile = 1 THEN myint END) END

FROM CTE