Linckia is easy to keep in a 300-400g tank with several hundred pounds of LR.
Otherwise, i strongly discourage keeping them. the overwhelming majority DO NOT take to spot feeding and are not scavengers - otherwise they would do fine in nearly any tank. It is clear success is highly correlated with the amount of available LR (surface area). They feed on microbial/bacterial/algal films or the microscopic creatures that feed on them. Every once and awhile someone reports one that spot feeds...it is exceedingly rare.
keep in mind too that they take 12-18 months to starve to death, so what appears to be working is often not. Anyone who has success with Linckia should have had that success at least 1.5 years.
Brittlestars and serpentstars are usually hardier - the bright red star has the most difficulty in acclimating of most in the hobby. Be careful on that front. Once established, most are very hardy, but should be spot fed. the green brittlestar should be avoided as it is a known predator in the wild.