I used to use Marquis many years ago and always had the same problem, they didn't really last. I play both finger style (with thumbpick only) and flatpick styles. I haven't tracked Darco but I seem to remember that Martin bought Darco about 30 years ago so they may have discontinued the brand.

These days I'm using medium gauge (.013 - .056) Martin Acoustic SP® 80/20 Bronze strings. The SP indicates Sustained Playability and I seem to be getting good life out of them. I don't have much experience with light gauge, they don't seem to have enough mass to bring out the full tonal range on my D-41 so I never buy them.

      - Mark