I have a friend who had a Calypso Signature and then a Ref 5se. The Calypso Signature is very good but the Ref 5se was better. He is now moving up to the Ref 6. He is using a pass .8 series amp.
I agree with you about the looks of the Ref 5se. The Last ARC Ref linestage I thought was good looking was the Ref 2 mk2. I am not a big fan of the Mac Audio Research look either. Though the Ref 6 is far better looking than the G series preamp.
But looks aside. the Ref 5se is a superb linstage and a real steal at the price some are going for used. I have owned and heard a lot of preamp in the last 30 years. The Ref 5se is one of the best if not thee best I have ever heard. I have not seriously listened to the Ref 6. I do think the Ref 5se is slightly better than the G series preamp.