Jonny,
What the hell do you expect people to say if they are indeed satisfied with the 5400ES? In my system it replaced a very good sounding DVP-S9000ES; my only other comparison is an Esoteric SA-60 in my cousin's system. The 5400ES portrays timbre extremely well, and has excellent frequency and dynamic range. Soundstage is very good. Compared to the unit it replaced, it sounds smoother yet with more detail and better low frequency response. Although I really like the Esoteric SA-60, I suspect in a side-by-side comparison I'd pick the 5400ES every time even without factoring in cost.
My vintage processor does not have HDMI, so I've only used the analog XLR from the 5400ES.
db