Hi Dave,
Since MN190 has a rather small 22mm fully illuminated circle (according to Orion/SW), I would go for a quality refractor. My 105mm refractor has a 44mm fully illuminated and corrected circle, and a 130mm refractor will most likely have a 55mm fully corrected circle. Having said that, a 22mm illuminated circle should be sufficient for KAF8300.
I believe a refractor would be more versatile, because you could image for a greater detail with just a flattener, and one day invest in a quality reducer and have a wider field with a faster f-ratio. I'm not sure if a reducer can used with MN190
MN190 and 130mm f/7 refractor when combined with KAF8300 will both have very similar image scale.
One more thing, I'm not sure how cooling times and backfocus compare for both designs.