That's the stupidest thing I've ever heard.
To the OP:
Both On3p and Moment are high quality boutique ski manufacturers and make a fantastic product using very similar materials (uhmw sidewalls, durasurf sintered bases, super thick edges, 3/4 wrap edges to avoid delamination, etc.). Some people on this site talk of Moment having shitty durability, although I don't know how much credence I'd give that; that may very well be due to a lack of edge detuning or other typical mistreatment as opposed to low manufacturing quality. The main difference I see between Moment's and On3p's constructions is that On3p uses a bamboo core and Moment uses various other core materials (I want to say aspen in some skis, pine in others, although I'm not sure. I just know that they don't use bamboo). In terms of the two specific skis, both the vice and FR will have very similar rocker camber rocker profiles; slightly larger than the industry standard for rockered park skis, with a decent amount of camber and a mid-stiff flex. In that respect, they are very similar. Vices are slightly narrower underfoot (half a centimeter), and are slightly tapered, while FR's are untapered. Also, FR's have an elliptical rocker profile and elliptical sidecut, meaning that the sidecut is tighter (17m) in the tip and tail than in the underfoot section (19m). This, combined with the rocker means that the further you lay them over on edge, the more of the tip and tail sidecut is engaged and the tighter turn they'll make. I believe vices just have a standard rocker profile and fixed radius sidecut. I, personally, would go with the FR because I like the feel of a bamboo core, I am intrigued by the concept of elliptical rocker and sidecut, especially for carving off the lips of jumps, I have had positive experiences with On3p before (I own a pair of caylors and they're the best ski's I've ever ridden) and I'd like to keep supporting the brand, I like a little bit wider profile in the park, and I like a symmetrical park ski (vices are slightly asymmetrical). But that's just me. Go for what ever sounds good to you given the aforementioned attributes.
Hope this helps,
Isak