I've used the Acratech GP inverted head for about 3 years on a D90 & it is rugged, reliable, cleanable & steady, even with the RRS omni package with a fisheye. The clamp only friction fits the rotor when inverted, but the design ensures a tight non-slip assembly with a 3/8 bolt. This might not be the case with a 3rd party clamp designed to fit on a threaded nipple. What I really like, besides the light weight, is that the rotor has markers every 30 degrees, allowing me to stand in one place while keeping track of the rotation stops: overlooked by most designers (Why? Haven't they used their stuff?). Ever hit a tripod leg with your foot mid-sequence?
Based on your needs, MFT/APSC, you won't be disappointed. But, like you plan to, I upgraded. With full frame, I've moved to the Arca-Swiss D4 (the geared version) - order of magnitude better - set "once & done". Heavier, but still portable & foldable within my Gitzo 1541T. Miss the rotor markers though.