My Rab Latok Alpine in size small weighs 15.5oz, so it's not too far fetched to think that every subsequent size is another ounce or so, meaning aprox 16.5 for med, 17.5 for large, etc etc.
The 2.5L pertex shield used in the kinetic is pretty popular fabric for wispy rainjackets. I used to own a OR helium that used the same fabric.
The 3L event in the latok alpine will be more breathable, a lot more durable and feel nicer against bare skin. The pertex kinetic is best for a rain jacket that will see most of its life in your backpack and the occasional passing storms. That said, it'll do fine be constantly worn while hiking in steady rain...just know it's limitations on durability (wear and tear from being underneath your pack) and comfort (limited breathability). The Latok Alpine is meant more for spring/shoulder season winter sports like mountaineering, skiing, snowboarding etc, as it's weight and durability are a little too overbuilt for typical trail use, but would provide the most comfortable experience (superior hood design and better breathability.)
Maybe look for something more in between these 2 extremes, like the Westcomb you mentioned, or a less stout eVent jacket like the Rab Pull-on, or those similar offerings by montane. There's plenty of eVent jackets in the 9-11oz weight range, but they might not be found at the price point of the 2 rabs discussed earlier.