Its proven that sarcophyton release alleopathic metabolites as well as xenia, gonipora, and lamellia.
the thing to note is that all corals are alleopatic in some manner... I know people who have had 99% sps then added a leather coral to their tanks and lost the leather with in days.
Some SPS are even agressive to one another!
Can it be done ?
Sure have a look at the Idol tanks in the SPS forum.
Is it safe?
Not really these corals in the wild MOST times would not be so close to one another. Usually you will see fields of Sarcophytons and then Fields of Acropora, montipora.
These are all in my readings .. check out Bornemans "corals" and calfo's - "coral propigation" some was internet and people on RC
Brian