I haven't listened to CT5 or ARC Ref 3 yet.
In the Opal,until a few days ago I was using Ken-Rad NOS VT231's in front and Sylvania NOS Tall Boys in back (I think front is input, back is output.) The sound was terrific with this combo. I recently substituted in front some NOS Russian 1578's purchased from Paul Lindemann (I think these are 6sn8's, but they work). So far, the sound is a bit warmer and full bodied, with perhaps a slight loss of detail. Need to listen some more and perhaps switch positions with Tall Boys to see if I like this arrangement better.
Never heard the EH's.
I don't think I will be parting with the Opal any time soon, although Roger has discontinued it and is coming out with a new top of the line pre called the Ruby, according to the Wyetech website.
Best,
Neal