Changing the sub distance is similar to using a variable phase control. A lot depends on your avr and how it's autocalibration deals with speaker/sub integration. It is more complex because of speaker roll off and how that relationship is with the filters. A sub/s close to the mains are easier to integrate and not be localized than subs close to the LP. A higher xo is easier to integrate with sub/s close to the mains. Getting the bass right in a system is one of the hardest things to accomplish.
Klipsch RF 7 based HT 7.4, Pioneer SC 35, Acurus 200 Five, Dayton 18 Ultimxa Dual Sub Cab(2), Dayton 18 Ultimax Large Vented Sub Cab (2), on Berhinger I Nuke DPS amps, Samsung BDP F 7500, Asus/My Book Live HPC 4 TB
Yaquin VK 2100 amp, McIntosh XR 5 speakers, Samsung BDP F 7500