Thanks so much for all of the above comments. It is always interesting, thought-provoking, and helpful to get the kind of input I have received so far.
As it turned out, I got an opportunity I could not refuse and so was unable to complete the comparison I had planned or consider the other options you all have offered/suggested, with the exception of the Rega Saturn, which I use in my secondary system and although which I like very much, I find it falls well short of my 390S in the A/B comparisons I did in my two systems.
WRT the aforementioned opportunity, my dealer brought over his last (and newest) ARC REF CD7 for me to audition A/B in my main system against my 390S. As many/most of you know, this unit lists for $9K. This one had about 100 hours on it (so not even fully broken in yet), came with an extra set of original tubes, came with an extra remote, all paperwork and boxes, and was/is in mint condition; essentially new. For "only" $6500. And on top of that, he gave me 85 percent back on a Rega Apollo I had purchased new and used sparingly in our HT when I wanted to crank up my Aerial 10Ts for better 2-channel sound than the Pioneer Elite Blu-Ray or Toshiba HD-DVD in that system can provide. So the price dropped from the realm of "low WAF" to, in her own words, "I can't believe I'm saying this, but that sounds like a pretty good deal." Out the door for ~ $5800, including tax.
As for the audition, it was a jaw-dropping experience, maybe about 20 percent of what I experienced when I first heard the Shindo Latour Field Coil Speakers in his home. The REF CD 7 bested my 390S in every way, producing a broader and deeper sound stage laced with even more detail, air, musicality (for me that means akin to being at a live performance) than the 390S, and provided the kind and degree of warmth I was after. So I snagged it, and those new tubes are now up to about 115 hours of use! The 390S has been in standby mode since late Friday night, probably a record except for vacations. And after reading the many post about the sonic benefits of ARC's free (except for insured shipping both ways) update to the CD7, I know I can eventually look forward to an even better musical experience, once I feel I can part with the CD7 for the requisite two or so weeks for the update. After which I will be parting with my 390S with my dealer's help or through this venue. (Actually, I would prefer to keep it and use it in my secondary system and sell the Rega Saturn, but that part of the domestic deal fell through!)
Again - thank you all for your thoughtful comments and suggestions. Now, I have to get back to listening! :-)