I totally agree with you on that LPG is a better player when paired with 70% of the popular TOTL IEM's out there on the market. This is due to the fact that brands like JH, UE, Shure, Westone, even audio-technica make stage monitors, which are often darker (read less treble) than neutral. With a boosted treble, LPG brings "air" and "timber" to these IEM. This is the case with SE5Way, as I have auditioned this exact pairing.
But when paired with IEM or heaphones that are actually neutral, usually those designed with serving audiophiles in mind, LPG becomes overly bright (read too much treble). The "accurate instrument timbre and note dynamics" becomes splashiness or "digital glare". This is the case, for example, with my UM Mentor and HD800S, which I consider close to neutral.
Another variable would be one's hearing. People with declined hearing would usually prefer brighter players and IEMs, like Ocharaku, some ALO's, K3003, etc.