I don't think plastic is a negative thing.Most of the YT videos are done by idiots obviously with no camera experience. But I did find one that was done by a single person performing the same test with handheld, Modosteady and Merlin Steadicam.
What I got from it was the Modosteady is barely better than my ability with my monopod method. However if you really want high quality the Merlin is the best of breed and it will enhance a shooter's existing skills for running shots.
I don't plan on doing much running but what I do most often is reveal shots and smooth jib arm simulations. If the Modosteady can do that satisfactorily, I'll be happy because it is so compact. But, I want to see some improvement over what I currently do with my monopod.
After looking at your work, I would repeat, you won't be satisfied with anything less than the real deal- a steadicam with arm and vest. Besides- while a steadicam Merlin is expensive $2500 in USD, here you can market your services as a steadicam operator and make a premium as a specialist on a shoot. You buy these toys we're toying around with and it will just serve your amateur level needs.
The way I figure it, the 3N1 has some other features I can place value on. I think what really caught my eye was the folding up and the tripod handle innovation. Manfrotto is very good at being innovative.