IF playing a MP3 file taxes less the processor than a 24/44.1 (big if, because it's maybe not true, I don't know)... maybe it would be interesting to have that facility to get more tracks/fx - plus the MP3 artifacts of each file might get less noticeable in a mix, giving results better than expected. And wouldn't it be nice to mix with lo-res (MP3) files for maximum tracks/fx then render the final mix in nonreal time using the original (24/44.1) files ?