We've been on some 15 Regent Cruises - but never on the Navigator, the Carribean, or in that high a cabin level.
Our last cruise was AMS-Monte Carlo on the Voyager in October 2014 - 14 nights. Short summary - food has declined somewhat over the years (their latest preoccupation is with sugar less desserts - does that mean no sweetener or "fake" sugar - no sight of caviar anywhere), shore excursions have become alot busier with most being included in the cruise fare, entertainment was really off this last cruise (only 4 production shows, 3-4 movie nights etc - not what you expect of a 14 night cruise - but the expert lecturer worked very hard (she lectured just about every day) and the cruise director also did the entertainment 2 nights (more than expected)). We like Regent because of the cabins are all the same from the lowest category H up through Concierge Level C (only Penthouses and up are different - we had a Penthouse B once on the Mariner) - this last cruise was in Concierge D (booked late since they offerred us a bump from the Navigator New England Cruise). Also, the open dining in the main dining room is much appreciated (dine whenever with whoever you want).
Feel free to ask for other specifics.