The Panasonic has undefeatable 4K upscaling. So your Envy isn't doing the 1080p - 4K upscaling.This is not an easy task. It isn't possible to do a "side-by-side" comparison in real-time, so that's out. Visual memory is likely not accurate enough to justify formal conclusions (or at least mine isn't). The only way to do this in a rigorous fashion would be to use still images, and even that is not a trivial task.
I do have photography experience, and could set up my DSLR on a tripod, shoot in Raw Format, use identical exposure settings, etc. I would then have to verify that my DSLR, as well as my computer monitor were capable of capturing a wide enough color gamut to demonstrate differences that are there.
The bottom line for me is that there is a difference, based on the science behind the filter's characteristics. And as I said, since the light cost is minimal, I use it to ensure I'm getting the best possible image from my projector. Anything beyond that would be interesting, but likely Academic, so I haven't taken the time to do this.
I'm using the Panasonic UB820. I bought this for use with prior Projectors, specifically the RS400, where HDR handling was poor on its own. It did provide several useful options to make it work better (along with custom gamma curves, an HD Fury Integral, and so forth). If I were buying a new player today, these features wouldn't matter, and my choice might be different.
But yes, all HDR tone-mapping, including the Optimizer, in the UB820 are disabled, wanting to deliver as "pure" a signal to the Envy as possible. And just for clarification, the Envy does not rely on HDR metadata, because this is notoriously unreliable.