In addition to the additional gain and loading flexibility, the Rhea has three inputs (individually configurable) and 2 main outs - SE out and BAL out. I use 2 tables and run the SE out into my Joule pre and the BAL out to my LS-25. Different amp/speakers follow each pre (effectively 2 systems with common sources in the same cabinet), and each system can detect either of the 2 'tables, switched via remote by the Rhea. For me, this is really useful. To my knowledge, there's really very little out there with as much flexibility as the Rhea.
OTOH, its sonic "flavor" will fit better in some systems and the ARC's will in others.