I compared my 8" f15.5 at WSP years ago with three 8" APOs. Early in the evening two of the three APOs gave better views, (I left my scope out in the sun all day uncovered for people taking photos) but after midnight when the seeing dropped well below .5 arc seconds and my scope cooled down only 1 of the APOs I would rate as very slightly better, perhaps very fine detail in Jupiters polar regions a tiny bit clearer. The other APO was a wash or perhaps a tad less sharp, the third was several steps down from my MCT and the other two APOs. We were all around 350x to 450x most of the time on Jupiter except the one APO, which struggled above 260x. Used up to 525x on Jupiter in the MCT with no hint of image breakdown or image getting to washed out or dim.
My MCT has no CA and less higher order abberations than any 8" APO that is F10 or faster. Also has a better figure than most. In excellent conditions 6" and 7" APOs dont come close from 20 years of comparrisions, hard to beat the resolution of a outstanding 8" with a smaller scope with just very good optics.
Where smaller APOs shine is when conditions are bad, wide field or imaging wide field is on the menu or you have temperatures dropping like a rock. If you live in an area that has generally poor conditions, get an APO.
And remember, not all APOs or MCTs are created equally. There can be significant variation even from the top manufacterures within a single brand and product line. Nobody makes perfect every time, though the top guys try harder to be close more often.