(1) the avoidance of a digital SRC. None the SRCs I have tried are completely transparent. I think Chris reported that he immediately noticed an improvement in his mixes when he adopted this source-mix-capture method.
(2) Not mixing at 44.1KHz. The addition of tracks that all have brick-wall anti-aliaising filters at around 20KHz produces a tiring top octave. This effect is not dissimilar from the bedroom-recordists results of tracking everything using a single bright condenser microphone. When the top octave is 20-40 KHz, the 10-20KHz region is much cleaner, and having just the stereo 20KHz filter for the mix capture is a tolerable necessity.