Thank you everyone for the thoughtful advice and input!
@Firecracker: I’m sad that the style of the black sandal doesn’t come in “silver metallic,” which is the color of the lace-up pair. I tried the pewter-brown color way at Nordstrom but it definitely reads as brown against my skintone and my wardrobe color palette is not very brown-friendly. Good idea on trying both pairs with potential outfits, although I prefer most of my shoes to “go” with most of my clothing.
@Sterling: I agree that the lighter silver color is more summer-appropriate… I am in the SF Bay Area, where summer nights are cool and the days never get above 90F. I wouldn’t say that black is as commonplace as in NYC, for instance, but I would wear a more strappy black sandal without hesitation.
@Diana: Oh, now that you’ve mentioned it I can see what you mean about the small toe cut out! Darn my tiny feet. However, both of these sandals feel like walking on clouds and I have fussy feet (in addition to small size + slightly narrow), so the toe cut out might be a detail I’ll have to sacrifice.
@Becky: I wear a lot of jewel tones year-round, as well as “true” colors like red and a very few pastels (mint and blush). An orange-coral is about as bright as I get. My coloring is pretty high-contrast (not pictured here but my hair and skin tone are a lot like Diana’s). I have a few pieces like a white skirt that I wouldn’t wear with the black bootie-sandals, but I’m fine wearing those with flat metallic sandals that I already own.
@Eliza: I didn’t mention it in my OP because it wasn’t apparent to me in the photos, but apparently I wasn’t looking closely enough! The silver-only photos actually show me wearing a size 5 in the lace-up sandals, which was too snug. I reordered size 5.5 which is much more comfortable.
Having parsed everyone’s feedback, I’m leaning towards the black pair… at least keeping them around and maybe doing another round of ordering. I have actually been looking for a pair of flat black sandals, to supplement my current metallic flat sandals for darker-toned summer outfits—which I think means that a black summer heel would be versatile. And these heels are comfy enough that I might not need another pair of flat black sandals, after all.
Time also to confess that my “older” bias was applied more towards the silver pair than the black pair. Although I really like the ghillie trend, somehow these seemed more “comfort” than trendy… wasn’t sure if I was just imagining things, but smittie and others have pointed out the same issue.