Producer I buy day olds from says she keeps her laying birds in separate sheds and changes one in Feb and one in Aug each year, selling on at 18 months-2 years at £6 a bird which folk locally to her (central Scotland) are happy to pay because they're not commercial brown hybrids but other colour hybrids like your sussex, bluebells, rhode rocks etc. They lay as well as the warren types but have a residual value at the end of their prime laying by going live to secondary homes. She has a secondary business selling young birds, day old to pol and finds the price and turnover for both markets are higher for coloured birds over brown ones - because people associate the brown hens with large scale commercial yards and rescue hens regardless of their conditions.
Again best to know your local market and potential sales margin on young and spent birds, but definitely at that level of production your trad purebreds aren't going to make the grade or they'd be the commercial preference.
May or may not work for you, depends on your local market for domestic hens.