Lightweight shavettes? The lightest shavette I've used is probably the Vanta Long Shavette (model RA109). In terms of shave quality, it's about equal to the heavier long shavettes but it's more manoeuvrable. Those long blades are much nicer to shave with than DE blades.
The two shavettes you've shown are the same just with different scales amirite. I imagine they'd shave the same.
I can't imagine the weight difference would amount to much between the two examples. The weight of the scales is really negligible when it comes to straights or shavettes.
I'm not a fan of DE shavettes. Injector bladed shavettes are as short as I'll go. My preference is for the weck style shavettes, which use personna shaping blades.
I like the Dovo shavette. With a fresh blade the resulting shave is closer compared to my straights but not as smooth. Need to test the Personna hair shaper blade in my Dovo maybe that will make it feel more like a straight.
Personally, my late 1800s 6/8th joseph rogers, or 7/8th wade butcher both near wedge ,forget shavettes they are designed to make you shy away from straights.