@nurbie
I have the Smart Effector on my RMax v2 with the molded cheapskates. The carriage adapters that come with the SE will fit perfectly on the molded cheapskates where the ball joints mount. 713Maker has some really nice stuff, but learn from my mistake and don't get the SE to ballcup arm adapter ($40). The problem with the 713Maker adapter is that it increases the distance of the arm articulation points between axis (not between the two arms of each axis, but between each axis) which makes the effector VERY susceptible to tilting. This wiki page describes it all very well.
Just order a set of 304mm (or larger) magball arms to go with the smart effector and you'll appreciate the upgrade from stock.
Let me know if you have any questions