Not every ski is for everyone. For what it is worth, all 8 people who work for ON3P use the Jeronimo or Kartel 106 as their park & hard day ski, aw well as about 1/3 of our team who use it for park over the Filthy Rich or Prester. Karl Fostvedt's promodel park ski is based upon the Jeronimo, and it's personally been my park/hard snow day ski for 5 years straight now, with my non-hard day ski being a 191cm BG or 191cm Wren, so I know how to drive a ski.
If you are a big skier hits lots of larger jumps, I can see wanting the stability of the Prester over the FR, Jeronimo, or Kartel series. But for most people, we find they are more than stable enough to function as both a park & all mountain ski.
Not to say your opinion is wrong, either, just pointing out that from our experience and that of our customers over the past 5 seasons we have been selling that ski, most find it works great as a park-capable all mountain ski and I very rarely hear people having issues with them being unstable. That said, each skier is different, so we appreciate your feedback.