I have a 7100 model (CUH-7116B).
The power-on button is flimsy, the glowing bar on the bottom cut has holes through which the light peeks through (not enough glue, Sony? really?), and it feels cheap.
They're starting to pull the same shit they did with the PSP "street" - which was probably the derpiest PSP I've ever seen in my life (and I've seen A LOT, trust me on this). Returned that shit the same day I purchased it. Their standards have clearly dropped ever since the PS2. I mean, ffs... Sony is a Japanese company run by westerner idiots! Never had these hardware corner-cuttings with Nintendo. Ever. Say what you will, but Nintendo makes some sturdy-ass hardware. It's probably the Japanese way of perfecting things, which Sony clearly doesn't have any more.
It comes with OFW 4.73 out of the box, just so you know ("Boost Mode" was introduced in 4.50), so there's no 4.05 hope. Only the initial models came with 3.70 (for whatever reason), the rest are 4.07+.
Oh, and the left stick on the controller feels mushy. It has maybe half the stiffness of the right stick, which is SO fucking distracting when playing any game that requires both. Another fine example of corner-cutting. Way to go, Sony...
It's not an "improved version, with a newer internal design, and more efficient architecture". It's the version that they're mass-producing these days, with as low cost as possible.