[Repeater-Builder] Duplexer vs Split Level Antennas

[wb0goa]

Have chance to install a DB 224 at 450' and another one anywhere below it. 
Using LDF6 on both runs. RF solid state 110 watts out. Wanting to know the pros 
or cons of running both antenna close together for more height with duplexer or 
spacing antennas for isolation without duplexer?