Jeff, for the vast majority of shavers coming from carts, I think the shave available from 'riding the pivot' will be closer, more comfortable, and healthier for the skin than that from a multi-blade cartridge. And that manner of use is almost completely devoid of what we think of as technique-angle, pressure, etc.
For we aficionados, who want a closer shave, there's some minor adjustments in angle that may help-in my case it was a steepening of the angle. I don't think this is any different than getting a new DE or SE razor, some of which may require some dialing in for the first few shaves.
Time will tell about the longevity of the plastic, but I'm not sure that unless one is very heavy handed or aggressive in inserting the blade, how the blade stops would get 'shaved off'. Seems pretty sturdy to me. But, I may be wrong about this, and time will tell.
Don't get me wrong-I still prefer shaving with a good, solid, all-metal, efficient razor. The shaves I can get from my Level 3 Charcoal OC, or .74 Wolfman, or .95 Timeless, or Cobra Classic, to name a few are as good as it gets for me. But the shaves I get from the OneBlades-both the Stainless and the plastic-are close enough to those shaves that it just seems remarkable to me. I gave one of the stainless models to a friend who was struggling with entry-level razors, Merkur 34C and EJ89, and from his very first shave with the OB, he was getting what he called great shaves.
So, I think these razors have their place in the market, and they may not be for the connoisseur.