Those .45s aren't new, they were made for the Army's Joint Combat Pistol program in the mid aughts. The extended barrels where for a custom rail mounted silencer that used a gasketed sleave that rode on the barrel IIRC.
No, it doesn't. The Compacts have a feed ramp, so that old frankengun proof of concept had that bit cut off. The barrels in the new factory G-SD barrels are simply based on that concept; they're not that old compact barrel. The engineers in Italy did up a new barrel and slide based on the idea.
It shows the benefits of a proactive back and forth relationship with external SMEs, though we're still not exactly agile (though for 500 years, I guess that's relative). And this very nearly did get lost in the cracks from the time of the original pitch, but Ernest loves the PX4 platform, and I happened to jump 'silos' here at Beretta over the last 7 years and remembered that gun and the discussions around it.
We know the PX4 does still need some ergo and texture work, but those existing international MIL and LE contracts have 10 year service stipulations, meaning those old tools need to stay active and refurbished. Projects like this keep the platform advancing and maintain a commercial market presence and business case in the meantime. Until then, Talon and Toni grip tape, and Boresight stippling cover that gap, and some new opportunities for modifications were discussed at SHOT. We're going to keep working on these and moving that all forward as long as we can.