I owned Jadis JA-80s for many years. Yes, I beleieve that they rolled off in the highs a little (this was the old, 1990 version, and I used Philips 6550s and Gold Lion KT 88s in them with Telefunken phase splitter and driver tubes), but I didn't care at all, as they got the midrange right and I believe most recordings to be a bit brighter than what I hear in the concert hall anyway, probably due to what Mr Tennis points out. I agree with the poster above about the 500s (even without the Da Hong mods, though they certainly do get rid of the classic tube sound), they were a different animal from the lower powered JA monoblock series; and Joe (Trelja) is quite familar with the sound of the newer models and you can count on his observations to be accurate.
In general, I would say that you don't buy a Jadis piece of equipment for aural thrills or necessarily to accurately reproduce everything that it is fed, you buy it because of the musical enjoyment it brings you. There are many pieces of equipment out there that will outperform it from a technical standpoint, but there are few that can match it from the standpoint of conveying the music (especially classical and acoustic music).
In general, I would say that you don't buy a Jadis piece of equipment for aural thrills or necessarily to accurately reproduce everything that it is fed, you buy it because of the musical enjoyment it brings you. There are many pieces of equipment out there that will outperform it from a technical standpoint, but there are few that can match it from the standpoint of conveying the music (especially classical and acoustic music).