If the reflectors are worth a damn 4 lamps is all you want or need over a 55. I would grab a Blue Plus and a Aquablue to replace one of the Blues and 10K that come with the units. If you like that look (1 blue plus, 1 aquablue, 10K and Blue) I would run the coral vue lamps you leave i the system 6 months and then change them out with the two you took out. At a year or so I would then go with all new lamps.
Then I would do this
Front
Blue Plus
Super Actinic
UVL Aquasun
ATI Aquablue