I actually saw both jackets this past weekend. My friend was looking into getting a leather jacket, so I went with him.
The alloy looks great, but too plain for me. Has CE armor, which is a plus, but my biggest complaint was the front zipper. It's exposed, unlike the other Alpinestars jackets that cover it up once zipped. The exposed medal zipper will scratch the living hell out of your tank.
The stunt looks alright, but I'm not a big fan of the looks. Have you thought about getting the Dyno jacket or TZ-1? Those looks pretty good too.
I just bought the red perforated stunt jacket. Its awesome, the fit is amazing compared to the icon crap I got rid of. I can prolly get you a deal on a stunt in a red 44 or blue 44 or 46. Pm me if your need.
just my 2 cents