The Jon pros are foam core and fairly soft. They are suuuuper light which I hate because I'm a jumper, and I'm not into rails really. When I land slightly backseat in these, I just flip out onto my back just like the spaceframe 1080s do. These are way too noodly for jumps in my opinion. But then again Durtschi kills big hits with them, so I guess its preference really.
The new material breaks like a mofo also. This means more core and sidewall blowouts.
they are really fun for messing around on rails, but the edges are also weak as hell.
I personally loved the old Heads because they were heavy and fucking stiff; perfect for big booters. But the new ones feel like a Salomon with the sidecut moved up towards the tip more.
All in all, they are a really fun ski for cruising around a resort park or something, but I wouildn't touch any big hits with them.