Ontology editor + why RDF?

Dear all, 
 
A quick question that I was hoping this forum might have some thoughts on:
we are looking for a new editing tool for our life science thesaurus EMTREE
(proprietary, multi-facted polyhierarchical, 260 k terms (50 k preferred,
210 k+ synonyms), > 10,000 nodes) and I am trying to convince the thesaurus
department to go to an RDF-based editor. I was wondering if anyone had any
thoughts on 
a- the best professional-grade ontology editor to use (serious alternatives
to Protege?), and
b- the best arguments to convince my company to start using RDF, both
internally and externally. 
 
Thanks for any comments! 

Anita
Anita de Waard
Advanced Technology Group, Elsevier
Radarweg 29, 1043 NX Amsterdam

+31 20 485 3838
 <mailto:a.dewaard@elsevier.com> a.dewaard@elsevier.com