I believe the cuts in the slide are to reduce weight and therefore speed up the cycling of the slide. DEVEL full house guns have similar cuts, but they are length-wise "scallops" in the slide. The windows are actually very practical. During a lull in the action, you glance at the grips and can determine if you should perform a tactical reload without removing the mag to look at the view holes. Other companies have had similar ideas. The original Detonics Combat Master magazines had a projection that stuck out the bottom of the mag when it was fully loaded so you could feel it with your finger. Even today, the BETA mag for AR Type weapons can be had with a clear cover so you can see your remaining rounds