Pass Labs X600.5 or a Pair of Classe Omicron's?

Time to make a choice. I know I want the amps close to my speakers for a short speaker cable run. It's not possible for me to A/B these amps. I'm looking at Pass Lab's X600's, around $6K used, (thinking I can do the .5 upgrade a little later on) OR the dual mono Classe Omicron, around $6K used, (thinking I can add a second one to run them bridged for each channel later on). Anyone with experience or opinions?

My system: Revel Salons, Classe CP-65 preamp, APL 3910 digital source. Not sure about cabling yet (ideas & suggestions welcome), but probably Transparent Ultra. Ref prices are crazy!

Thanks,
Doc