Stern has a history of making their game quality worse as time progresses. Not really any different than the "classic stern" model from the 1980s either.
from decreasing wire thickness, to not using hardened parts, to changing leg thickness, to changing bracket thickness, frankly the list is endless. if you want to see this play out, go to the Pinball Hall of Fame. You can ask Tim Arnold, he will gladly tell you how Stern continually changes things to save them money, but making his job harder and more expensive as an operator. Or you can just look at the games. Check out any Stern that is 1 year old or greater. Then compare it to a 1990s Williams game. You'll see it.
Frankly mounting boards under the playfield is never a good idea. Using thin wire (or RJ wire in the case of Spike), again, not a good idea. It may be fine for the home owner. If that's where the bar is set (low), then Stern will do OK. But for an operator, nothing in the Spike system is better. Also with all the surface mount components (which have a terrible reliability factor when bolted to the bottom of a playfield), at least for most, are not serviceable. If you're OK with being a "board swapper" i guess the Spike system will do you fine. But frankly i like to do component level repair, and nothing in the Spike system allows this.
Time will tell. I hope i'm wrong. But i have a feeling... and it's not a good feeling...