Of course the best fidelity is lossless. The question is whether or not it's a perceivable difference. For video, telling 1080p from 720p depends on the source material and screen size/viewing distance. For audio, as long as the masterings are the same, I'd expect the differences to be minimal and unobservable to the vast majority of people, including those with relatively high end systems. Here is the slideshow for an interesting paper on MP3 vs CD using a dedicated listening room and high end equipment, where the test subjects included "trained listeners" and "expert listeners":
To the extent I can extrapolate, these high bitrate lossy core soundtracks would strain the ability of "trained listeners" to distinguish them from the lossless versions, and I expect most of the time, the "expert listeners" wouldn't be able to tell them apart, either, as long as the masterings are the same, so that you're listening to the same soundtrack encoded lossless vs. lossy.
Well, we can chalk it up to snake oil and I'm no expert but some will probably swear up and down that they hear a difference. I believe you that there is probably no perceivable difference but if I had a choice, I would pick lossless over "lossy"