you guys have to remember, that uvls resulting in a lesser haunt uptime, unless you refresh your dots manually. but in almost all cases you'll refresh your dots with sb:ss when uvls proccs. also breath has much haste on it, affliction strongest stat atm. so i dont believe that uvls is that much better than lfr breath.
UVLS should be quite far ahead of the LFR BOTH in simcraft numbers and if I were to do it myself. But the usefulness of UVLS is also more limited by your reaction-speed and general dot management, than the usefulness of BOTH.
Generally, higher itemlevel = better item
UVLS is extremely random (all RPPM trinkets are.. but this one is worse) and I find it extraordinarily annoying to play with. I use it as demo ofc, but even with the Everlasting Affliction glyph I have trouble keeping up a 100% critting doom, with a 530 ilvl UVLS.