RE set out I think , to make a quieter running Bullet ... because quite is BIG in India. And so is a very low idle ! Deep low thump thump thump thump . But failed a bit in the valve train noise dept.
Very true; almost everyone who knows anything or has any interest in Bullets over here (in India) complains about the excessive valvetrain noise in the UCE's predecessor, the AVL. Collector interest in the old iron-cylinder models has ramped up incredibly high in the past several years, while more powerful, efficient, clean-running AVL's, despite their being hardly different technologically or visually, seem to be like rejected stepchildren selling for half the price or less. Because they're noisy. I'm serious, everybody mentions it, just about every owner is/was frustrated with it. Iron Bullets properly built are extremely quiet, one foreign owner here described riding his as a "Zen-like" experience, whatever that means. Not practicing Zen myself, I'll just say they do have a certain kind of lazy, undemanding, smooth, calming "magic" about them. There is nothing distracting or unpleasant there at all (unless you want to ride fast).
So yes, when it came to designing the UCE's, I'm sure that quietness, along with reducing maintenance, was at the top of their list of priorities. Overall, on average, hydraulics have done what they needed to for them, but as noted, for people who want to extract more predictable additional performance and who don't mind a little extra maintenance and who loathe the idea of having to pull off a top-end to replace potentially defective lifters (or change to a thinner, unlikely available cylinder base gasket, etc etc), I'd think the solids could provide real-world advantages.
-Eric