there's a slight noise floor advantage in the higher sample rates as well, not something often mentioned or talked about, read bob katz mastering audio, he mentions this.
From the book -"Moving to high sample rates automatically provides a signal-to-noise advantage, so 16 bits at 96kHz is 3.4 dB quieter than at 44.1, sonically equivalent to about 16 1/2 bits. Noise-shaping at high sample rates can allow shorter wordlength files with very low psychoacoustic noise floor - the noise can be made extremely low and flat in the audible band and the shaping moved above 20kHz. In fact, 16-bit noise shaped dither at 96kHz can sound as good as 24-bit/44.1, as I discovered one day when I accidentally left 16-bit dither on while working at 96kHz."
As I understand the text above, the perceived lower noise floor / perceived increase in dynamic range is only attributed to the fact that at high sample rates in a dithered system, significant portions of the required dithering noise can reside in the higher, inaudible frequency range. In other words the dithering noise level within the audible band drops because it is moved up the spectrum out of our hearing range..
Note that the effect only takes place in a dithered system where there is no quantization "noise" (quantization distortion).
Also note that he was talking about the perceived noise floor of a 16 bit dithered system. The noise floor of a 24 bit recording is -144db. How much quieter does it need to be. None of this silliness does anything about the noise floor of what you are actually recording, which in the best of circumstances can only realistically be -110 or so.
Of course you can always argue that lots of people covet the sound of tape, which had a snr of 60-70db and if it's played back on vinyl the snr goes down significantly.
Chasing signal to noise down below -100dbfs is pretty pointless. Especially when most things will get limited to the point where they have a crest factor of less than 10db.