IMHO the mini monitor + sub only matches full range speakers if an active crossover is included, or, at least, some high-pass on the main amp.
Otherwise, you will still be limited by power handling and distortion from your 5inch main "woofers", and dynamic capabilities / max SPL will be limited.
Such an active crossover could introduce noise and distortion (may I advise Sublime Acoustic’s K231 crossover or the brand new K235 currently at reduced launch price?)
I was recently forced to switch from my huge 4 ways active horn system to a pair of tiny Dali Zensor 1 mini monitors and I have to admit, there are a few things that the cheap and tiny Dalis do better than my monsters (out in the room on stands, they really disappear and throw a deeeeep soundstage) but ultimately I was really missing the scale, the slam, and the flow of my big system.