Polycistronic expression

[Mega]

Hi everyone, 

Bacteria and plastids are capable of having many coding sites per mRNA molecule. 

that wold give us a mRNA of       5' cap - RBS - CDS1 - spacer - CDS 2 - spacer - CDS3 - 3'UTR

Now I read the rumor that each CDS needs its own ribosome binding site (SD-sequence)... True? 

On the other hand there is this paper saying that for some chloroplast genes, no RBS are needed for expression neither in chloroplasts nor in E.Coli ..

http://www.ncbi.nlm.nih.gov/pubmed/9520261

So what is true when linking two genes? Include another RBS or not??