Just curious if anyone here prefered the sound of the Yamaha U3 over the YUS5 for any reason?
Not exactly, John, but I did have an experience that relates to your question. . .
When I played a YUS5 and two U3s recently in southern California, the YUS5 sounded head and shoulders above the U3s. However, the dealer said one of the U3s was used (I can't remember how old, but far from new), and the other, which was new, he recommended not playing because it was just out of the box and hadn't yet been prepped.
A week or two later in Portland I played a new YUS5 next to a new fully-prepped U3. It was a completely different experience. The YUS5 still sounded what I'd call more "refined" or "polished" but the U3 sounded so much better than the old one had in L.A. (or the new one that hadn't yet been worked on) that I was VERY surprised and a bit confused.
What happened? U3s have been significantly altered by Yamaha in recent years (details provided in several places in the forum by the Venables in the U.K.). Larry Fine mentions how Yamaha has moved away from its previous arguably overly bright tone. This has not, to my ear, been a problem with YUS5s, but it had (past-tense) been a problem with U3s. No more, however.
Moreover, old U3s have the rep of getting progressively too bright and too few people bother to get them toned back down with voicing (including many dealers selling used ones). So the used one I played in L.A. had this additional disadvantage.
In any case, I still liked the YUS5 better in Portland, even when the comparison was against a new ready-to-roll U3. However, the fairly large difference in cost made me feel that I would have gone with the U3 if I were heading in that general direction. This was a big surprise, especially after my experience in L.A. It is also, I admit, a very subjective call indeed, and I'm sure if others respond to this there will likely be a wide variety of other opinions.
As you know, in the end I've ordered a (silent) C2. Even here, I have to admit that the YUS5 has a more polished sound to my ear even than a C2. That said, however, the very large difference in sound board size and string length can overcome a host of other differences that might otherwise favor a smaller piano.
Indeed, in comparing the sound of the C2 (5'7") to a C3 (6'1"), two pianos that are mostly the same except for the one issue of size, the C3 sounded so much better that I was tempted to spend way too much and cram far too much piano into the livingroom in order to get that terrific sound.
Bottom lines here? The new U3 has come up so much that I think it makes the call between U3 and YUS5 a bit more of a challenge than it would have been in the past. Also, when it comes to pianos, size can play such a major role that it can override other issues. (So as not to confuse, for those less familiar with YUS5s and U3s, those two are identical in size.)