Both Mermaid I and Raja Ampat diving are excellent, though I did not do the two together. Did Komodo trip on Mermaid I in June 2014 and Raja Ampat 5 months later on MSY Seahorse. Both were great trips but I'd put Komodo in front by a nose.
Mermaid I is a great boat, one of the best of the many liveaboard vessels that I have sailed on. The senior Divemaster Hari the Finn is superb, particularly with his briefing and getting the best itinerary out of the prevailing conditions. Lots of photography opportunities in RA - macro, big stuff, coral etc.
Night dives are particularly rewarding in that part of the world and unless you particularly don't like it, try to get as many night dives as there are on offer.