I don't have any pics but it would basically look like a a very fluffy version of a normal BSL - hens would be majority black with some red-orange coming in through the hackle and breast; males would be barred with some red/gold leakage. Unless you're going with a backwards sex-link cross - Barred male and red female. In which case you could expect to see both males and females Barred with red/gold leakage. Hope you're intending on working with bantams though - I've been seeking out a Standard Red Cochin for a while, with no luck. They exist - I've seen the pictures! - but nobody is talking and nobody is selling.
Sex Linkage isn't strictly for egg-production. The common high-production BSLs and RSLs available from hatcheries are only high-production because they have been bred for it for many generations. Assuming you had access to the correct colors, you could breed a sex-linked Oriental Gamefowl that laid 10 eggs a year. The benefit of a sex-linked Cochin would be to guarantee the sex of standards and enable the easy sexing of bantams. Sex-linked chicks also sell more easily (or, the hens do, anyways).