The Magnus radius is tighter than the Filthy Rich.
Do note, the elliptical sidecut radius is designed to be straighter underfoot and tighter in the tips and tails, so when you load up and flex the skis, they carve a lot tighter than the listed radius. Flip side is what you are skiing flat in and out of features, the skis are more stable because the sidecut is straighter underfoot.
As for this choice...I'm obviously biased but the main differing factor is rocker. We're 100% sold on our rocker designs which is why everyone on our team is skiing Magnus or Kartel 98/108 in the park, so we have no concerns with stability. That said, a full camber ski does have a different, more locked in feel. I'd say if you want more locked in and stable feel, go HG. If you want something more playful/jibby, go Magnus.
Hope that helps.