Hey Alex, My Sterns do feel "different" from my B/W -- they feel less substantial is how I would put it. That means they "feel cheaper" though my experience with their reliability has been very good. I've had a POTC, LOTR AND FGY for many years and the worst I've had is a broken armature link on an auto plunger and a loose wire. I have noticed that my flipper coil on my new Tron is very noisy sometimes recently so I'll keep an eye on it.
I notice when I switch playing from a B/W to a Stern that it takes some time to adjust to the different feel.
Having said all that, I'm a WOZ buyer and I do believe JJP is really going to up the ante on quality of build. Stern has done all it can to keep its build of material cost down.
Give it some time, play some other Sterns near you and see how you feel.