They are both sealed so quite similar in response. The larger cone will have more linear power. Just be aware that room response increases at lower frequencies so a sub that has a flat response to 20Hz anechoic will need calibration in almost every domestic situation (if used for music). This is room related and the way low frequencies excite modes and get boosted.
My speakers have 15" woofers and roll off at 25Hz and in practice I find I prefer the sound without any assistance from my 15"subwoofer when listening to music.
I note you have ML speakers. I am not sure if it will be easy to match. Panels are limited in bass and dynamic range. Your desire for more bass may be related to a desire for a more dynamic presentation. Anyway all I am saying is system synergy is just as important as the subwoofer specs.
My speakers have 15" woofers and roll off at 25Hz and in practice I find I prefer the sound without any assistance from my 15"subwoofer when listening to music.
I note you have ML speakers. I am not sure if it will be easy to match. Panels are limited in bass and dynamic range. Your desire for more bass may be related to a desire for a more dynamic presentation. Anyway all I am saying is system synergy is just as important as the subwoofer specs.