So a little revival of this. I had been using a GSG 1911-22 since I had been shooting 1911's for a year, but no longer do so. I grabbed a Taurus Tx22, as it most closely correlates to the VP9 grip/trigger, and the price for the gun/trigger/flat wire recoil spring, and adjustable rear sight was hard to argue with. I'll be getting the red dot version once it's on the market.
It uses a glock front sight, and a proprietary adjustable rear sight. The rear sight width appears to be the same as a factory glock sight, and it uses a factory glock sight. That said, is there any front-sight only upgrade on glocks that improve the sight picture?